Särtryck ur: Acta zoologica ; 3(1922)

Särtryck ur: Acta Zoologica ; 3(1922)

No description available.

Purpose: The general aim of this thesis was to increase the understanding of biomaterial surface modifications and local delivery of osteoporosis drugs for bone integration. We therefore (i) characterised and investigated model surface coatings for controlled drug delivery in a rat tibia screw model (ii) elucidated the effect of surface treatment for activation of complement system in vitro. Materials and methods: Bisphosphonate was immobilised directly to implant surfaces by two methods. In the first method, bisphosphonate was bound via a crosslinked fibrinogen layer to titanium surfaces. In the second method, stainless steel screws were first dip coated in a TiO2 solgel, and thereafter incubated in simulated body fluid (SBF). The so prepared thin calcium phosphate layer on titania bound then bisphosphonate directly with high affinity. The drug release kinetics was determined in vitro by 14C marked alendronate that was quantified with scintillation techniques. The screws were inserted in the metaphysis of rat tibia and the mechanical fixation monitored by screw pullout measurements after 2 or 4 weeks of implantation. In order to compare two different osteoporosis drugs, bisphosphonate and strontium ranelate, stainless steel and PMMA screws were inserted in the tibial metaphysis of rat for 4 and 8 weeks. Bisphosphonate was then delivered subcutaneously and strontium ranelate orally during the whole implantation period. The mechanical fixation was analysed by pullout force measurements, and bone architecture studied by micro-computed tomography (μCT). The immune complement activation on sol-gel- and smooth titanium surfaces was analysed in human blood plasma before and after annealing of titanium at 100-500ºC or upon UVO-treatment for up to 96 hours. Results: Bisphosphonate coated screws enhanced the screw pull out force after 2 weeks of implantation by more than 30% (fibrinogen coating) and by 93% after 4 weeks (sol-gel derived TiO2 coating). Systemically administered bisphosphonate enhanced the mechanical screw fixation after 4 weeks by more than 96% and after 8 weeks by more than 55% as compared to strontium ranelate treated animals (p = 0.00). Strontium ranelate treatment did not show significant improvement of screw pullout force after 4 and 8 weeks, compared to control. The immune complement surface deposition from blood plasma vanished irreversibly after Ti heat treatment at 250-300 ºC during 30 minutes or after UVO exposure for 24 hours or longer. Tentatively, changes in surface water/hydroxyl binding upon heat- and UVO treatments were observed by XPS and infrared spectroscopy. Conclusions: The results show that fixation at short implantation time (weeks) of orthopaedic implant can be enhanced by immobilised bisphosphonate on stainless steel or titanium implants. Systemic delivery of strontium ranelate showed no significant effect on implant fixation in rat tibia, and we hypothesise therefore that strontium ranelate will not become a power tool to increase the early implant fixation, but may be beneficial at longer times. Heat annealing or UVO-treatment of titanium surfaces change the surface hydroxylation, leading to decreased immune complement deposition from blood plasma.

No description available.

Särtryck ur: Geologiska föreningens i Stockholm förhandlingar ; 40(1918):3

Särtryck ur: Geologiska föreningens i Stockholm förhandlingar ; 44(1922):3-4

Background. Load carriage is a heavy task often performed in soldiers, other professions and sports, and is known to be strenuous on the body. Aerobic capacity which includes oxygen uptake and maximal oxygen uptake is the body’s ability to create energy using different substrates and is for assessing performance in load carriage. Soldiers are known to have a high aerobic capacity but it is not known to what degree load carriage has an effect on aerobic capacity, maximal performance or substrate utilization. Nor is it know how substrate utilization is affected during load carriage in participants with different body compositions. Aim. The aim of the current study was to investigate differences in oxygen consumption and substrate utilization with and without military gear and to study the relationship between body composition and substrate utilization in Swedish ground combat soldiers. Methods. Seven male and one female (24.5±3.5 years) participated in the current study. VO2, VO2peak, Respiratory Exchange Ratio (RER) and performance in the form of levels completed in the VO2max test were measured with an Oxycon Pro during a biological calibration and a modified Bruce protocol for VO2max. Body composition was measured with a bioelectrical impedance analysis. Shapiro-Wilks test was used to test for normality, Two-way repeated measures ANOVA was used for analysis of the main effects with gear, main effects of the levels and interaction effects between the tests. Paired samples t-test was used to analyze the differences in VO2peak, VO2 and RER. Spearman’s correlation was used for correlations between fat percentage and levels completed in the VO2max test. Results. The results of the current study showed a significantly lower absolute (p=0.02) and relative (p=0.01) VO2peak with gear compared to without gear. Significantly higher submaximal VO2 values with gear were also found in all active levels of the biological calibration and VO2max test as well as significantly higher RER values in all levels of the VO2max test with gear compared to without. A significant decrease in levels completed in the VO2max test (49%) with gear was also found (p<0.001). No correlations between substrate utilization, body composition and levels completed were found. Conclusion. The main findings of the current study were that VO2peak decreased and submaximal VO2 and RER levels were increased when wearing military gear. No correlations between muscle mass, fat mass or fat percentage and RER and levels completed were found. The findings can help better the understanding of the physiological demands during load carriage and can act as a guide for future load carriage workers, trainers and athletes.

No description available.

Svenska elevers intresse för de naturvetenskapliga ämnena har de senaste decennierna minskat vilket i sin tur även har påverkat deras prestationer i de berörda ämnena. Elevers kunskaper i dessa ämnen har visat sig minska i flera olika mätningar. Forskning tyder på att naturvetenskapliga begrepp har tendens att kännas främmande för elever. Syftet med studien har varit att undersöka sex stycken olika lärares uppfattningar om den undervisning i de naturvetenskapliga ämnena som syftar till att utveckla elevers begreppsförändring. Studien har utformats efter den konstruktivistiska lärandeteorin och hur den uppfattar begreppsförändring. Sex stycken lärare med olika typer av yrkeserfarenhet och som är stationerade på tre olika skolor har medverkat i sex stycken kvalitativa intervjuer. Metoden som har nyttjats i denna kvalitativa studie är tematisk analys. Resultatet av min studie visar på elva stycken olika teman som har framkommit ur informanternas utsagor. De teman som jag har funnit är Förkunskaper, Vardagsfenomen, Diskussioner, Begreppskarta, Textläsning, Intresseväckande introduktion, Samtal mellan elever, NTA, IKT/Praktiskt arbete, Bristfälliga föreställningar och Utbildning/Fortbildning. Min slutsats är att för blivande och befintliga lärare inom de naturvetenskapliga ämnena, kan resultatet i denna studie bidra till ökad förståelse för olika didaktiska verktyg kring begreppshantering samt att de även kan appliceras i andra ämnen. / Swedish student´s interest towards the science subjects has decreased during the last decades, which has led to an impact regarding their performance in these subjects. Several measurements have indicated a decrease in student´s knowledge in the science subjects.  Research shows that the science vocabulary has a tendency to feel frightening for the students. Focus is to examine six different teachers’ perceptions regarding their teaching in the science subjects that aims to develop students´ conceptual change. Six teachers with different professional experiences at three different schools have taken part in six qualitative interviews. Thematic analysis has been chosen as qualitative method in this study. The result of my qualitative study shows eleven different themes, which the six informants think are suitable for an introduction of new science terms. These are Previous Knowledge, Everyday Phenomena, Discussions, Concept Map, Text Reading, Interest awakening introduction, Conversations between students, NTA, ICT/Practical Work, Misconceptions and Education. My conclusion is that for existing and future teachers within the science subjects the results may contribute to a better understanding for different didactical tools regarding conceptual treatment and that they are place able even in other subjects.