| 1. |
- Burvall, Anna, et al.
(författare)
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Communication modes in large-aperture approximation
- 2007
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 32:6, s. 611-613
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Tidskriftsartikel (refereegranskat)abstract
- Simplified versions of the communication modes in the Fresnel domain are derived when the system apertures are large. The approximate modes, which are in the form of spherical waves and sinc functions with a spherical curvature, give physical insight into the communication modes approach and the basic limits of free-space optical communication systems. They also show that Gabor's information theory is readily derived from the communication modes.
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| 2. |
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| 3. |
- Landberg, Rikard, et al.
(författare)
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Dose response of whole-grain biomarkers : alkylresorcinols in human plasma and their metabolites in urine in relation to intake
- 2009
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 89:1, s. 290-296
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Tidskriftsartikel (refereegranskat)abstract
- Background: Alkylresorcinols (ARs), phenolic lipids almost exclusively present in the outer parts of wheat and rye grains in commonly consumed foods, have been proposed as specific dietary biomarkers of whole-grain wheat and rye intakes. Objective: The objective was to assess the dose response of plasma ARs and the excretion of 2 recently discovered AR metabolites in 24-h urine samples in relation to AR intake and to establish a pharmacokinetic model for predicting plasma AR concentration. Design: Sixteen subjects were given rye bran flakes containing 11, 22, or 44 mg total ARs 3 times daily during week-long intervention periods separated by 1-wk washout periods in a nonblinded randomized crossover design. Blood samples were collected at baseline, after the 1-wk run-in period, and after each treatment and washout period. Two 24-h urine samples were collected at baseline and after each treatment period. Results: Plasma AR concentrations and daily excretion of 2 urinary AR metabolites increased with increasing AR dose (P < 0.001). Recovery of urinary metabolites in 24-h samples decreased with increasing doses from ≈90% to ≈45% in the range tested. A one-compartment model with 2 absorption compartments with different lag times and absorption rate constants adequately predicted plasma AR concentrations at the end of each intervention period. Conclusion: Both plasma AR concentrations and urinary metabolites in 24-h samples showed a dose-response relation to increased AR intake, which strongly supports the hypothesis that ARs and their metabolites may be useful as biomarkers of whole-grain wheat and rye intakes.
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| 4. |
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| 5. |
- Magnusson, Ylva, 1967, et al.
(författare)
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Lipid imaging of human skeletal muscle using TOF-SIMS with bismuth cluster ion as a primary ion source.
- 2008
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Ingår i: Clinical physiology and functional imaging. - 1475-0961 .- 1475-097X. ; 28:3, s. 202-9
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Tidskriftsartikel (refereegranskat)abstract
- Intramyocellular lipids are of importance in lipid-related diseases. The techniques in this field are limited because of a lack of adequate tools for localization of various lipids. The most usual methods for the localization of lipid distribution in the skeletal muscle are histochemistry and fluorescence probes. Different chromatography methods and mass spectrometry techniques have also been used for lipid identification. Our aim was to localize the spatial distribution of lipids in their native forms by using static time-of-flight secondary-ion mass spectrometry (TOF-SIMS). Human percutaneous skeletal muscle biopsies were obtained from the middle part of the lateral vastus muscle in the right leg of healthy adolescents with a body mass index >30. Samples were prepared by high-pressure freezing, freeze-fracturing and freeze-drying, and analysed by imaging TOF-SIMS equipped with a Bi3+ cluster ion gun. In the positive spectra, we identified phosphocholine, cholesterol, diacylglycerol, phospholipids and triacylglycerol. Phosphocholine was localized to the edge of the fibre, representing the sarcoplasma or endomysium. Weak cholesterol signals were observed in the intracellular areas. High diacylglycerol and low triacylglycerol signal intensities were seen in intracellular spaces of the transversal area of the muscle fibre. In the negative spectra, we identified fatty acids. We observed co-localization of fatty acids and diacylglycerol, which may indicate lipid-storing parts of the skeletal muscle. Thus, TOF-SIMS imaging can be used to depict the heterogeneous localization of lipids in human skeletal muscle.
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| 6. |
- Malmberg, Per, 1974, et al.
(författare)
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Imaging of lipids in human adipose tissue by cluster ion TOF-SIMS
- 2007
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Ingår i: Microsc Res Tech. - : Wiley. - 1059-910X .- 1097-0029. ; 70:9, s. 828-35
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Tidskriftsartikel (refereegranskat)abstract
- Biopsies of human subcutaneous adipose tissue were taken from healthy donors. Samples were high-pressure frozen, freeze-fractured, and freeze dried. Imaging mass spectrometry of samples was performed in a TOF-SIMS mass spectrometer equipped with a bismuth cluster ion source. Blood vessels, the connective tissue, and adipocytes can be seen in TOF-SIMS images. Blood vessels were found labeled by a high content of sodium ions and potassium ions in their lumen and phosphocholine signal in smooth muscle cells of the vessel wall. The connective tissue showed high signal levels of CN(-) fragments, derived from proteins and nucleic acids. Adipocytes showed high signal levels of phosphocholine and cholesterol ubiquitously in their membranes and diacylglycerols in some membrane sites. The central part of adipocytes showed high levels of triacylglycerols and fatty acids. These results are in accordance to those of biochemical studies; however, a precise spatial localization of lipids in adipocytes is demonstrated with MS imaging.
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| 7. |
- Malmberg, Per, 1974, et al.
(författare)
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Localization of lipids in the aortic wall with imaging TOF-SIMS
- 2007
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Ingår i: Biochim Biophys Acta. - 0006-3002. ; 1771:2, s. 185-95
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Tidskriftsartikel (refereegranskat)abstract
- Time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) was utilized to address the issue of localization of lipids and inorganic ions in healthy rat aorta and human atherosclerotic plaque. Pieces of rat aorta were high pressure frozen, freeze-fractured and freeze dried. The samples were analyzed by imaging TOF-SIMS equipped with a Bi(1-7)(+)-source. Reference lipid samples were analyzed and compared to data obtained by analysis of the rat aorta samples. Fatty acids, cholesterol, oxysterol and diacylglycerols were detected and localized. A heterogeneous lipid distribution could be shown in the aorta, where the lamellae of the aorta, distinguished by imaging of CN(-), appeared enriched in cholesterol, oxysterol and diacylglycerols, while the smooth muscle tissue, identified by imaging of PO(3), appeared enriched in phosphocholine. Palmitic/palmitoleic acid and stearic/oleic acid appeared to be heterogeneously distributed over the aorta with high concentration areas located especially in the tunica media region of the aorta. Human atherosclerotic plaque showed an irregular cholesterol distribution mainly located in spots in the intima region with elongated diacylglycerol regions located mainly in the media region.
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| 8. |
- Martinsson, Per, 1971-, et al.
(författare)
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Communication modes with partially coherent fields
- 2007
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Ingår i: Journal of the Optical Society of America A. - 0740-3232. ; 24:10, s. 3336-3342
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Tidskriftsartikel (refereegranskat)abstract
- We develop a theory for the description of partially coherent wave fields in linear optical systems in terms of the so-called communication modes. The communication modes are the singular functions and singular values of the appropriate propagation kernels. In particular, we show that optical fields of any state of coherence may be readily propagated through deterministic systems using the modal representation based on the system properties. The relation of the communication modes to the conventional coherent-mode representation is discussed, and expressions for the effective degree of coherence in the optical system are derived. The results are illustrated by numerical examples in optical near-field geometry.
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| 9. |
- Martinsson, Per, 1971-, et al.
(författare)
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Communication modes in scalar diffraction
- 2008
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Ingår i: Optik (Stuttgart). - : Elsevier BV. - 0030-4026 .- 1618-1336. ; 119:3, s. 103-111
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Tidskriftsartikel (refereegranskat)abstract
- The communication modes are a useful concept in studies of optical resolution, wave propagation, and image synthesis. We present an overview of earlier results on the communication modes in scalar diffraction theory. Besides the general theory, the modes are reviewed for the far-field and Fresnel regimes, and new eigenequations are derived for wide-angle diffraction. We prove a conjugate relationship between the transmitting and receiving modes in a general symmetric system. We also suggest an approximate method for far-field and Fresnel domain propagation, in which propagation amounts to a rotation of each mode in the complex plane. The main focus is on the near-field communication modes, where we present numerical examples of the modes and coupling strengths for a near-field geometry with a sub-wavelength size receiving domain. These results provide insights, for example, into the understanding of near-field scanning probe techniques.
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| 10. |
- Martinsson, Per, 1971-, et al.
(författare)
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Scanning optical near-field resolution analyzed in terms of communication modes
- 2006
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Ingår i: Optics Express. - 1094-4087. ; 14:23, s. 11392-11401
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Tidskriftsartikel (refereegranskat)abstract
- We present an analysis of scanning near-field optical microscopy in terms of the so-called communication modes using scalar wave theory. We show that the number of connected modes increases when the scanning distance is decreased, but the number of modes decreases when the size of the scanning aperture is decreased. In the limit of small detector aperture the best-connected mode reduces effectively to the Green function, evaluated at the center of the scanning aperture. We also suggest that the resolution of a scanning optical near-field imaging system is essentially given by the width of the lowest-order communication mode.
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| 11. |
- Martinsson, Per, 1971-
(författare)
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Structural Information Content of the Optical Field
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The communication modes are a mathematical technique for the description of structural information in optical fields. These modes are orthogonal, optimally connected functions characteristic of the optical system. Mathematically they are obtained by the singular value decomposition (SVD) of the operator that represents the field propagation. In this dissertation, the foundations of the technique are described, and the theory is extended and applied to a variety of specific systems. In the Fresnel regime, the communication modes are closely related to the prolate spheroidal wavefunctions (PSWF). Within this approximation, the numerical propagation of the field in a one-dimensional optical system in terms of the PSWFs is demonstrated and the problem of assessing the best achievable realization of a given target field is addressed. Simplified equations for field propagation are presented. Approximate modes in large-aperture systems are derived and shown to agree with Gabor's theory on optics and information. The longitudinal resolution of an axicon is analyzed in terms of the communication modes. It is shown that in a generalized axicon geometry the communication modes are expressible in terms of the PSWFs, and that in usual circumstances a version of the large aperture approximation applies, resulting in quadratic waves in the aperture domain and sinc functions in the image domain Eigenequations for the communication modes in scalar near-field diffraction are derived and applied to a simplified scanning near-field optical microscope (SNOM) geometry. It is suggested that the resolution of a SNOM system is essentially given by the width of the lowest-order communication modes. The best-connected mode is shown to effectively reduce to the Green function. Within the context of random fluctuations the communication modes are defined for the cross-spectral density of partially coherent fields. These modes are compared to the well-known coherent modes. Expressions for the effective degree of coherence are derived, and it is demonstrated that optical fields of any state of coherence may readily be propagated through deterministic systems by means of the communication modes. Results are illustrated numerically in an optical near-field geometry. The communication modes theory is further extended to vector diffraction on the basis of Maxwell's equations. The polarization properties of the electromagnetic communication modes as represented by the Stokes parameters are analyzed numerically for an example of a near-field geometry.The work presented in this dissertation shows that the communication modes are an advanced, versatile tool that can be applied to deterministic and random, scalar and electromagnetic optical systems in far-field and near-field arrangements. The method is likely to find further uses in applications such as polarization microscopy.
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| 12. |
- Nielsen, Elisabet I., et al.
(författare)
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Developmental Pharmacokinetics of Gentamicin in Preterm and Term Neonates : Population Modelling of a Prospective Study
- 2009
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 48:4, s. 253-263
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Tidskriftsartikel (refereegranskat)abstract
- Background and objective:Preterm and term newborn infants show wide interindividual variability (IIV) in pharmacokinetic parameters of gentamicin. More extensive knowledge and use of predictive covariates could lead to faster attainment of therapeutic concentrations and a reduced need for concentration monitoring. This study was performed to characterize the population pharmacokinetics of gentamicin in preterm and term neonates and to identify and quantify relationships between patient characteristics and IIV. A secondary aim was to evaluate cystatin C as a marker for gentamicin clearance in this patient population.Methods:Data were collected in a prospective study performed in the Neonatal Intensive Care Unit at the University Children's Hospital, Uppsala, Sweden. Population pharmacokinetic modelling was performed using nonlinear mixed-effects modelling (NONMEM) software. Bodyweight was included as the primary covariate according to an allometric power model. Other evaluated covariates were age (postmenstrual age, gestational age [GA], postnatal age [PNA]), markers for renal function (serum creatinine, serum cystatin Q and concomitant medication with cefuroxime, vancomycin or indometacin. Covariate-parameter relationships were explored using a stepwise covariate model building procedure. The predictive performance of the developed model was evaluated using an independent external dataset for a similar patient population.Results:Sixty-one newborn infants (GA range 23.3-42.1 weeks, PNA range 0-45 days) were enrolled in the study. In total, 894 serum gentamicin samples were included in the analysis. The concentration-time profile was described using a three-compartment model. Gentamicin clearance increased with the GA and PNA (included in a nonlinear fashion). The GA was also identified as having a significant influence on the central volume of distribution, with a preterm neonate having a larger central volume of distribution per kilogram of bodyweight than a term neonate. Cystatin C and creatinine were not correlated with gentamicin clearance in this study population. The external dataset was well predicted by the developed model.Conclusion:Bodyweight and age (GA and PNA) were found to be major factors contributing to IIV in gentamicin clearance in neonates. Based on these data, cystatin C and serum creatinine were not correlated with gentamicin clearance and therefore not likely to be predictive markers of renal function in this patient population. Based on predictions from the developed model, preterm neonates do not reach targeted peak and trough gentamicin concentrations after a standard dosage regimen of 4mg/kg given once daily, suggesting a need for higher loading doses and prolonged dosing intervals in this patient population.
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| 13. |
- Rundgren, Malin, et al.
(författare)
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Neuron specific enolase and S-100B as predictors of outcome after cardiac arrest and induced hypothermia.
- 2009
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Ingår i: Resuscitation. - : Elsevier BV. - 1873-1570 .- 0300-9572. ; 80, s. 784-789
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To assess the prognostic value of repetitive serum samples of neuron specific enolase (NSE) and S-100B in cardiac arrest patients treated with hypothermia. METHODS: In a three-centre study, comatose patients after cardiac arrest were treated with hypothermia at 33 degrees C for 24h, regardless of cause or the initial rhythm. Serum samples were collected at 2, 24, 48 and 72h after the arrest and analysed for NSE and S-100B in a non-blinded way. The cerebral performance categories scale (CPC) was used as the outcome measure; a best CPC of 1-2 during 6 months was regarded as a good outcome, a best CPC of 3-5 a poor outcome. RESULTS: One centre was omitted in the NSE analysis due to missing 24 and 48h samples. Two partially overlapping groups were studied, the NSE group (n=102) and the S-100B group (n=107). NSE at 48h >28mug/l (specificity 100%, sensitivity 67%) and S-100B >0.51mug/l at 24h (specificity 96%, sensitivity 62%) correlated with a poor outcome, and so did a rise in NSE of >2mug/l between 24 and 48h (odds ratio 9.8, CI 3.5-27.7). A majority of missing samples (n=123) were from the 2h sampling time (n=56) due to referral from other hospitals or inter-hospital transfer. CONCLUSION: NSE was a better marker than S-100B for predicting outcome after cardiac arrest and induced hypothermia. NSE above 28mug/l at 48h and a rise in NSE of more than 2mug/l between 24 and 48h were markers for a poor outcome.
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| 14. |
- Rung, Emilia, 1974, et al.
(författare)
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Progesterone-receptor antagonists and statins decrease de novo cholesterol synthesis and increase apoptosis in rat and human periovulatory granulosa cells in vitro
- 2005
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Ingår i: Biology of reproduction. - : Oxford University Press (OUP). - 0006-3363 .- 1529-7268. ; 72:3, s. 538-45
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Tidskriftsartikel (refereegranskat)abstract
- Progesterone-receptor (PR) stimulation promotes survival in rat and human periovulatory granulosa cells. To investigate the mechanisms involved, periovulatory rat granulosa cells were incubated in vitro with or without the PR-antagonist Org 31710. Org 31710 caused the expected increase in apoptosis, and expression profiling using cDNA microarray analysis revealed regulation of several groups of genes with functional and/or metabolic connections. This regulation included decreased expression of genes involved in follicular rupture, increased stress responses, decreased angiogenesis, and decreased cholesterol synthesis. A decreased cholesterol synthesis was verified in experiments with both rat and human periovulatory granulosa cells treated with the PR-antagonists Org 31710 or RU 486 by measuring incorporation of [14C]acetate into cholesterol, cholesterol ester, and progesterone. Correspondingly, specific inhibition of cholesterol synthesis in periovulatory rat granulosa cells using 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (lovastatin, mevastatin, or simvastatin) increased apoptosis, measured as DNA fragmentation and caspase-3/7 activity. The increase in apoptosis caused by simvastatin was reversed by addition of the cholesterol synthesis-intermediary mevalonic acid. These results show that PR antagonists reduce cholesterol synthesis in periovulatory granulosa cells and that cholesterol synthesis is important for granulosa cell survival.
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| 15. |
- Sandström, Ulf, 1953-, et al.
(författare)
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Tvärvetenskap - en analys
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Forskare arbetar i allt större utsträckning i tvärvetenskapliga projekt. I rapporten analyseras dels varför forskningen utvecklas på detta sätt, dels hur forskningsfinansiärer arbetar för att understödja tvärvetenskapliga initiativ.Rapporten är resultatet av ett projekt som bedrivits inom analysenheten vid Vetenskapsrådet. Docent Ulf Sandström har varit projektledare.
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| 16. |
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