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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Physico-chemical investigations of, and characterization of model membranes for, lipid-peptide interactions /

Wessman, Per, January 2009 (has links)
Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 3 uppsatser.
2

Lipidförändrande effekten av niacin

Amin, Benai January 2020 (has links)
Niacin som upptäcktes för 70 år sedan är en substans som än i dag studeras mycket kring. Men fortfarande är man inte överens om niacin verkligen har en signifikant effekt på kardiovaskulära sjukdomar. Verkningsmekanismen för niacin är ännu oklar, men forskning pekar på att hämmad syntes av triglycerider resulterar i en minskad LDL-koncentration. HDL-ökningen tros bero på en hämmad nedbrytning av HDL-partiklar, och därmed blir en större mängd HDL kvar i blodet. Nuvarande lipidbehandling består först och främst av en balanserad kost och ökad fysisk aktivitet. Vid otillräcklig effekt sätts läkemedelsbehandling in, som består av statiner, resiner, fibrater och hämmare av kolesterolupptag i tarmen. Syftet med detta arbete är att studera om niacin, både som monoterapi och i kombination med andra lipidsänkande preparat, har en påverkan på blodlipidvärdena HDL, LDL och triglycerider, hos människor. Genom systematisk litteratursökning har artiklar samlats in för att kunna sammanställa resultaten. Alla tio studierna som inkluderades kom fram till att niacin, antingen i kombination med andra lipidsänkande preparat eller som monoterapi, har en signifikant effekt på lipoproteinerna. Resultaten visade en LDL-sänkning upp till 58,5% (i kombination), den högsta HDL-ökning var 50% (monoterapi) och högsta triglycerid-sänkningen var 51,7% (i kombination). Dock är niacins effekt på LDL och triglycerider likartad eller sämre än dagens lipidsänkande preparat. Niacin har däremot en större effekt när det kommer till HDL-ökningen. Därför bör det göras flera och större studier gällande niacins effekt på HDL. Om studierna visar positiva resultat bör det övervägas för användning hos patienter med låg HDL. Dock orsakar biverkningarna en sämre följsamhet, och eventuella analoger till niacin bör utvecklas, detta för att inte gå miste om en eventuellt potent HDL-ökande behandling. Slutsatsen för detta arbete är att i människa har niacin en signifikant effekt på lipoproteinerna LDL och HDL samt lipiden triglycerider. Behandling med niacin leder till en sänkning av LDL och triglycerider samt en markant ökning av HDL.
3

Dödsgott med käk i kistan : En GCMS- och FTIR-analys av kermik från ett vikingatida gravfält i Alsike hage, Alsike sn, Uppland

Forsgren, Andreas January 2007 (has links)
<p>This paper deals with the connection between food and burial habits during the late Iron Age in present-day Sweden. The archaeological material used in the study consists of 16 potsherds from a burial site at Alsike hage, Alsike parish, in the province of Uppland in east-central Sweden. On these potsherds have been conducted FTIR- and GCMS-analyses, in order to see what types of food have been deposited in the burials. Furthermore, the result of the GCMS-analyses has been compared to contemporary material from both burial sites and settlement sites, in order to establish whether differences between the compared materials exist. The analyses show that there are differences between the material from burial sites compared with the material from settlement sites, but not any particular differences between the material from different burial sites. Among these differences we can see that the settlement sites show: a higher amount of total lipid content, a higher amount of vessels which contained lipids indicating that food was heated in them, a higher amount of vessels which contained lipids from crop products as the only content, and a higher amount of vessels which contained lipids from ruminant animals. The interpretation of these results is also discussed in the paper. Furthermore, the results of the FTIR-analyses also shows a good correlation with the results from the GCMS-analyses, it seems that the organic “foodcrusts” analysed with FTIR indeed stem from the same meal indicated by the GCMS-analyses.</p>
4

Dödsgott med käk i kistan : En GCMS- och FTIR-analys av kermik från ett vikingatida gravfält i Alsike hage, Alsike sn, Uppland

Forsgren, Andreas January 2007 (has links)
This paper deals with the connection between food and burial habits during the late Iron Age in present-day Sweden. The archaeological material used in the study consists of 16 potsherds from a burial site at Alsike hage, Alsike parish, in the province of Uppland in east-central Sweden. On these potsherds have been conducted FTIR- and GCMS-analyses, in order to see what types of food have been deposited in the burials. Furthermore, the result of the GCMS-analyses has been compared to contemporary material from both burial sites and settlement sites, in order to establish whether differences between the compared materials exist. The analyses show that there are differences between the material from burial sites compared with the material from settlement sites, but not any particular differences between the material from different burial sites. Among these differences we can see that the settlement sites show: a higher amount of total lipid content, a higher amount of vessels which contained lipids indicating that food was heated in them, a higher amount of vessels which contained lipids from crop products as the only content, and a higher amount of vessels which contained lipids from ruminant animals. The interpretation of these results is also discussed in the paper. Furthermore, the results of the FTIR-analyses also shows a good correlation with the results from the GCMS-analyses, it seems that the organic “foodcrusts” analysed with FTIR indeed stem from the same meal indicated by the GCMS-analyses.
5

Interaction between cobalt nanoparticles and DPPC at pulmonary conditions / Växelverkan mellan koboltnanopartiklar och DPPC vid pulmonära förhållanden

Sommer, Paula January 2021 (has links)
Nanomaterial produceras och används alltmer i tekniska lösningar för att förbättra t.ex. materialegenskaper. Eftersom ett materials egenskaper förändras när det är i nanoskala så påverkas även dess toxikologiska egenskaper. För närvarande finns det ett flertal rapporter om oavsiktligt bildande av metalliska nanopartiklar, Me NPs, vid byggarbetsplatser, vilket riskerar att byggarbetarna exponeras för att andas in dessa partiklar.  På grund av nanomaterialens storleksberoende egenskaper så är inte dagens toxikologiska utvärderingsmetoder sällan anpassade för dessa typer av material. Att undersöka växelverkan mellan Me NPs och pulmonella biomolekyler och utveckla metoder för analys därför av hög prioritet.  I detta examensarbete har en metod för upplösning av det pulmonellt ytaktiva ämnet fosfolipid 1,2-dipalmitoylfosfatidylkolin, DPPC, baserat på sonikering i vattenbad testats och utvärderats. Den simulerade lungvätskan Gambles lösning har testats och utvärderats som en möjlig lösning för att studera växelverkan mellan DPPC och Co NPs. Växelverkan mellan dess komponenter och Co NPs har studerats med hjälp av PCCS, NTA samt ATR-FTIR. Då examensarbetet genomfördes under den pågående Covid-19 pandemin har anpassningar i det experimentella arbetet gjorts med hänsyn till det rådande läget. PCCS visade att vid upplösning av DPPC i lösningen så minskade sonikering omfattningen av sedimentationen och den resulterande storleken på liposomerna låg inom intervallet mellan 50 och 70 nm i ultrarent vatten och mellan 30 och 40 nm i Gamble’s lösning. Skillnaden i liposomstorlek tros bero av växelverkan mellan komponenterna i Gamble’s lösning och DPPC, vilket även observerades med FTIR och överensstämmande med litteraturen. Den relativa skillnaden i liposomstorlek i de olika lösningarna observerades också med NTA, men experimentella problem kan ha påverkat resultaten. Gamble’s lösning hade en inverkan på Co NPs i lösningen, bland annat genom att uppmätta partikelkoncentrationer bestämde med hjälp av PCCS och NTA var mindre än hälften av motsvarande koncentration initialt i ultrarent vatten (vid 0 h). En trolig förklaring är att den högre jonstyrkan hos Gamble’s lösning orsakar snabb sedimentation och/eller snabb upplösning av Co NPs. Tillsättning av DPPC till en lösning av Co NPs i Gamble’s lösning släckte ut effekten, vilket indikerar en växelverkan mellan Co NPs och komponenter i Gamble’s lösning. Jämförelse av normaliserade integraler från ATR-FTIR med DPPC i Gamble’s lösning utan Co NPs och när lösningen exponerades för en Co NP film visade en signifikant skillnad efter 90 min och vid sköljning. Baserat på projektets resultat så föreslås Gamble’s lösning att bytas ut på grund av dess växelverkan med de olika komponenterna samt att liposomstorleken studeras mer i detalj. Framtida studier uppmuntras omfatta en upprepning av ATR-FTIR- mätningarna samt en frisättningsstudie av Co NPs i olika lösningar. / Nanomaterials, NMs, are increasingly produced and applied in technical applications to enhance, e.g. material properties. Since material properties change when in nanoscale, they influence their toxicological properties. There are also numerous reports of incidental formation of metallic nanoparticles, Me NPs, at construction sites, which may place workers at risk of occupational exposure by inhaling these materials. However, because of NMs size-dependent properties, current standard toxicological evaluation methods are not always well suited to these types of materials. Investigations into interactions between Me NPs and pulmonary biomolecules and method development for analysis of these interactions are therefore of high priority. In this master thesis, a description on how to dissolve the pulmonary surface active phospholipid 1,2-dipalmitoylphosphatidylcholine, DPPC, via water bath sonification has been elaborated and evaluated. The simulated lung fluid, Gamble’s solution, has been tested and evaluated as a possible medium to study interactions between DPPC and cobalt (Co) NPs under more realistic laboratory conditions. Interactions between the sample components have been studied using Photon cross-correlation spectroscopy, PCCS, Nanoparticle Tracking Analysis, NTA, and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy, ATR-FTIR. Since the master thesis study was conducted during the onset of the Covid-19 pandemic, adjustments related to experimental work had to be made. PCCS showed that sonication of the DPPC solution reduced the extent of sedimentation, and the resulting size range of liposomes in solution was in the range between 50 and 70 nm in ultrapure water and between 30 and 40 nm in Gamble’s solution. Observed differences in liposome size are believed to be due to the interaction between the components of Gamble’s solution and the DPPC. This was also observed in the IR- spectra and comparable with literature findings. NTA measurements similarly visualize the relative difference in the size of the liposomes in the different media, but difficulties with the experiments may have affected the results. Gamble’s solution affected the Co NPs, such that measured particle concentrations of the NPs by means of PCCS and NTA were approximately less than half of the initial observations in ultrapure water (at 0 h). A likely explanation is that the high ionic strength of Gamble’s solution induces either fast sedimentation and/or rapid dissolution of the Co NPs. The addition of DPPC to Co NPs in Gamble’s solution cancelled this effect and suggest interactions between Co NPs and Gamble’s solution. Comparison of the normalized integrals of the ATR-FTIR- spectra of DPPC in Gamble’s solution with and without exposure to a Co NP film showed a significant difference after 90 min and upon rinsing the flow cell. Based on these results, an alternative to Gamble’s solution is suggested due to its interaction with other experimental components and that DPPC is used at a lower concentration investigation on liposome sizes are made in more detail. In addition, the ATR-FTIR measurements should be repeated, and dissolution studies of Co NPs in different synthetic media are encouraged in future studies.
6

OCT (Optical Coherense Tomography) : Teknik och tillämpning

Lundkvist, Stefan January 2013 (has links)
Before year 1895, the doctors could only make a probable diagnosis based on what the patient could tell and it was hurt and there was no discernable change to the outside of the body. With X-ray, it was possible to see inside the patient without first cutting it, you can say that the X-ray was the starting point for diagnostic imaging.The further development of X-ray gave CT (Computed Tomography), where X-ray tubes and detectors rotate around the patient while the patient table moves. Besides CT also developed MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography) and Ultrasound. Common to these methods is that the produced 3D images.In 1990 a completely new approach for diagnostic imaging, OCT (optical coherence tomography), by measuring the phase shift and the intensity of reflected light, it provides real-time and non-destructive measurements (in vivo) a resolution of 1 to 15 microns, much higher than all other standard imaging techniques. You could say that OCT machine can be compared to ultrasound, which uses the reflection of sound waves to interpretation.The first OCT machines were of type TD (Time Domain), these had low resolution and low scanning speed. In 2005 came the SD-OCT, they had higher resolution and scanning speed, SD stands for spectral domain, SD-OCT is sometimes called FD-OCT as Fourier transformed signals and operating in the frequency domain.The development of OCT machines are only in their infancy, resolution, scanning speed and accuracy will increase all the time, this allows new uses and ways to diagnose developed. OCT can be used in such Oncology, MSD (Musculoskeletal disorders), cardiovascular medicine, teeth, nerves, but the largest field is the eye and then the back of the eye called the retina (retina).This thesis is limited to the eye, the purpose is to provide input to those who are likely to purchase an OCT-machine, but also show the measurement data OCT-machines are performing and how to use the OCT-machine more than to see age-related macular degeneration. Another aim is to increase understanding of the physics behind an OCT-machine for ease of understanding the output given.The manufacture/model that have selected for evaluation are Zeiss Cirrus 4000, Topcon 3D OCT-2000 and Heidelberg Spectralis, the reason is that there are only these three on the Swedish market and all are SD-OCT. The way to evaluate OCT-machines is to scan performance and what the various analysis programs can handle. Furthermore, each OCT-machine scans the macula and optic disk on a experimental person/ reference eye, in order to get the output of the precision, or if you want to call it repeatability, which is very important if one wants to follow a solitary disease course.The conclusion of this thesis is to OCT machines are quite similar. When it comes to ease of use when doing scans is the Cirrus is lightened by the use of the extra screen where you always look eye (iris camera), which makes it easy to adjust the sharpness and position of the mouse buttons. Topcon and Heidelberg is not difficult to use but requires more experience of the person making the OCT scans. Most measurement functions in the analysis program is Topcon and Heidelberg and best accuracy/repeatability is Heidelberg, both the macula and RFNL.OCT machine is a good tool to use on the anterior segment, but in the case the precision allows the precision used to monitor RNFL thickness changes in those with glaucoma. / <p>Validerat; 20131029 (global_studentproject_submitter)</p>

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