| 1. |
- Bolinius, Damien Johann, et al.
(författare)
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Sorptive Capacities of Nonpolymeric Plant Lipids for Hydrophobic Chemicals Determined by Passive Dosing
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:3, s. 1278-1286
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Tidskriftsartikel (refereegranskat)abstract
- Vegetation plays an important role in the partitioning, transport, and fate of semivolatile hydrophobic organic chemicals (HOCs) in the environment. Leaf/air partition ratios (K-leaf/air) of HOCs are highly variable for different plant species. The differences cannot be fully explained by the fraction of lipids in the leaves or the thickness of the cuticle. Our goal was to elucidate the importance of non polymeric lipids in determining K-leaf/air To do this, we extracted organic matter from 7 plant species using solvents that do not extract the polymeric lipids cutin and cutan, to yield extractable organic matter (EOM). We used passive dosing to determine the partition ratios of selected HOCs between the EOM of the leaves and our reference lipid, olive oil (K-EOM/olive oil) In addition, we measured analogous partition ratios for three lipid standards. Proton nuclear magnetic resonance (NMR) spectroscopy was used to characterize the composition of lipids. Differences in K-EOM/olive oil of two polychlorinated biphenyls and four chlorinated benzenes were below a factor of 2 in the plant species studied, indicating that the reported differences in K-leaf/air are not caused by differences in the sorptive capacities of nonpolymeric lipids or that our EOM is not representative of all nonpolymeric leaf lipids.
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| 2. |
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| 3. |
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| 4. |
- Drake, Anna Maria, et al.
(författare)
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Ankle dorsiflexor muscle performance in healthy young men and women: reliability of eccentric peak torque and work measurements
- 2001
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Ingår i: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1651-2081 .- 1650-1977. ; 33:2, s. 90-96
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were: (i) to assess the test-retest intrarater reliability of eccentric ankle dorsiflexor muscle performance in young healthy men and women using the Biodex dynamometer; and (ii) to examine different statistical indices for the interpretation of reliability. Thirty men and women (age 22.5 +/- 2.5 years, mean +/- S.D.) performed three maximal eccentric contractions at 30 degrees/second and 90 degrees/second, with 7-10 days between test sessions. Reliability was evaluated with three intraclass correlation coefficients (ICC1,1, ICC2,1 and ICC3,1), and was excellent for peak torque (ICC 0.90-0.96) and good to excellent for work (ICC 0.69-0.83), with no discernible differences among the three ICCs. Method errors, assessed by the standard error of the measurement (S.E.M.) and S.E.M.%, were low. The Bland & Altman graphs and analyses indicated no significant systematic bias in the data. In conclusion, measurements of eccentric ankle dorsiflexor muscle performance in young healthy individuals using the Biodex are highly reliable.
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| 5. |
- Drake, Anna Maria, et al.
(författare)
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Assessment of contractile and noncontractile components in human skeletal muscle by magnetic resonance imaging.
- 2002
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Ingår i: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 25:2, s. 251-258
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Tidskriftsartikel (refereegranskat)abstract
- A magnetic resonance imaging (MRI) technique for the assessment of contractile and noncontractile components of human skeletal muscle is described, and the inter-rater and intra-rater test-retest reliability for repeated measurements from the same MR image are examined. Twenty cross-sectional MR images from the right lower leg were obtained from 30 healthy young men and women (mean age 24.1 years, SD 3.3). The anatomical cross-sectional area (aCSA; cm2), the cross-sectional area of noncontractile components (Noncon; cm2), the contractile cross-sectional area (cCSA = aCSA minus Noncon; cm2), and the relative amount of Noncon (%), of the ankle dorsiflexor muscle compartment were determined for each slice using a computer-based image analysis system. Reliability for repeated measurements of the slice with the largest aCSA for the 30 subjects was analyzed by two raters on two different occasions. Inter-rater reliability on both occasions, assessed by the intraclass correlation coefficient (ICC), was excellent for cCSA (ICC3.1 = 0.99) and Noncon (ICC(3.1)
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| 6. |
- Drake, Anna Maria, et al.
(författare)
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Reliability of isokinetic ankle dorsiflexor strength measurements in healthy young men and women
- 1999
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Ingår i: Scandinavian Journal of Rehabilitation Medicine. - : Informa UK Limited. - 0036-5505 .- 1940-2228. ; 31:4, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- The purposes of this study were: (i) to determine the test-retest reliability of isokinetic ankle dorsiflexor strength measurements in young healthy adults using the Biodex dynamometer, and (ii) to examine several statistical measures for the interpretation of reliability. Thirty men and women (mean age 23 +/- 3 years) performed three maximal concentric contractions at 30 degrees/s, 60 degrees/s, 90 degrees/s, 120 degrees/s and 150 degrees/s. Reliability of peak torque, work and torque at a specific time were assessed by calculating the intraclass correlation coefficient (ICC 2,1), Pearson product moment correlation coefficient (r), standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV), and by plotting the differences between observations against their means. Isokinetic tests of ankle dorsiflexor strength in healthy young adults using the Biodex dynamometer were highly reliable (ICC 0.61-0.93). It is recommended that test-retest reliability analyses include the ICC and assessments of measurement errors (SEM, ME or CV), as well as graphs to indicate any systematic variations in the data.
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| 7. |
- Drake, Anna Maria, et al.
(författare)
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Reproducibility of isokinetic ankle dorsiflexor strength and fatigue measurements in healthy older subjects.
- 2007
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Ingår i: Isokinetics and Exercise Science. - 1878-5913 .- 0959-3020. ; 15:4, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine the test-retest (two occasions seven days part) reproducibility of isokinetic (Biodex) concentric (CON) and eccentric (ECC) ankle dorsiflexor strength and fatigue measurements in older subjects using several statistical methods. Thirty healthy men (n=15) and women (n=15) aged between 70 and 85 years participated in the study. To determine the reproducibility of strength measurements, the 30 individuals performed three maximal CON and ECC contractions at 30°/s and 90°/s. The intraclass correlation coefficient (ICC_{2.1}) for CON and ECC strength measurements was high and ranged from 0.94 to 0.98. Bland & Altman graphs and analyses indicted no systematic bias. The standard error of measurement (SEM), representing the smallest change that indicates a real improvement (or deterioration) for a group of individuals, was small (< 2.3 Nm). The smallest real difference (SRD), representing the smallest detectable change that indicates a real improvement (or deterioration) for a single subject, was also small ('error bands' from −7.2 Nm to 5.6 Nm). A high correlation (Pearson's r > 0.94) between CON peak torque at 30°/s and 90°/s, as well as ECC peak torque at 30°/s and 90°/s, suggested that any of these two velocities could be used as a reference. To determine the reproducibility of fatigue measurements, 28 of the 30 individuals performed 50 maximal CON contractions at 60°/s. Reproducibility of the loss in work (work fatigue) and the relative loss in peak torque, comparing the first three to the last three contractions (3-3), was determined and the ICC was 0.71 and 0.60, respectively. In addition, the SEM was small (< 8.4%) and the 'error bands' to define the SRD for a single subject were also small (from −23.5% to 24.5%). In conclusion, these values indicate small measurement errors and thus provide a clinically acceptable basis for testing ankle dorsiflexion strength and fatigue of the dominant side in healthy older people.
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| 8. |
- Drake, Anna Maria, et al.
(författare)
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The structure and function of the ankle dorsiflexor muscles in young and moderately active men and women.
- 2003
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Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 95:6, s. 2416-2424
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate determinants of ankle dorsiflexor muscle (DF) strength and size in moderately active young men and women ( n = 30; age 20–31 yr). Concentric (Con) and eccentric (Ecc) strength were measured isokinetically. Magnetic resonance imaging was used to determine the muscle cross-sectional area (CSA). Multiple biopsies were obtained from the tibialis anterior muscle to determine total numbers, areas (Area I and II) and proportions (Prop I and II) of type I and II fibers, respectively, and relative contents of myosin heavy chain (MHC) isoforms MHC1, MHC2a, and MHC2x. Women had lower Con and Ecc strength (24 and 27%; P < 0.01), smaller CSA (19%; P < 0.001), lower Ecc DF specific strength (strength/CSA) (10%; P < 0.01), and smaller Area I and Area II (21 and 31%; P < 0.01) than men. Prop I, MHC1, estimated total number of fibers, and Con DF specific strength were similar for both sexes. Con DF strength was up to 72% determined by CSA and Prop I, and Ecc DF strength was up to 81% determined by CSA, Prop I, and sex; variables other than CSA explained at most 9%. Body weight and fiber areas explained >50% of the variation in CSA. In conclusion, CSA was the predominant determinant of DF strength, CSA was to a great extent determined by the body weight and the sizes of muscle fibers, and sex differences in Ecc specific strength require further study.
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| 9. |
- Flansbjer, Ulla-Britt, et al.
(författare)
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Reliability of gait performance tests in men and women with hemiparesis after stroke.
- 2005
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Ingår i: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1650-1977 .- 1651-2081. ; 37:2, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To assess the reliability of 6 gait performance tests in individuals with chronic mild to moderate post-stroke hemiparesis.DESIGN: An intra-rater (between occasions) test-retest reliability study. Subjects: Fifty men and women (mean age 58+/-6.4 years) 6-46 months post-stroke.METHODS: The Timed "Up & Go" test, the Comfortable and the Fast Gait Speed tests, the Stair Climbing ascend and descend tests and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC(2,1)), the Bland & Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%).RESULTS: Test-retest agreements were high (ICC(2,1) 0.94-0.99) with no discernible systematic differences between the tests. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (< 9%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual, was also small (13-23%).CONCLUSION: These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in individuals with chronic mild to moderate hemiparesis after stroke.
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| 10. |
- Flansbjer, Ulla-Britt, et al.
(författare)
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What change in isokinetic knee muscle strength can be detected in men and women with hemiparesis after stroke?
- 2005
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Ingår i: Clinical Rehabilitation. - : SAGE Publications. - 1477-0873 .- 0269-2155. ; 19:5, s. 514-522
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the intra-rater (between occasions) test-retest reliability of isokinetic knee muscle strength measurements in subjects with chronic poststroke hemiparesis and to define limits for the smallest change that indicates real (clinical) improvements for stroke patients. Subjects: Fifty men and women (mean age 589±6.4 years) 6=±46 months post stroke, able to walk at least 300 m with or without a unilateral assistive device. Methods: Maximal concentric knee extension and flexion contractions at 608/s and 1208/s, and maximal eccentric knee extension contractions at 608/s, with the paretic and nonparetic limbs, were performed seven days apart using a Biodex dynamometer. Measures: Reliability of the maximum peak torque measurements was evaluated with the intraclass correlation coefficient (ICC2,1), the Bland and Altman analyses, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). Results: Test retest agreements were high (ICC2,1 0.89-0.96) with no discernible systematic differences between limbs, angular velocities and modes. The SEM%, representing the smallest change that indicates a real (clinical) improvement for a group of subjects, was relatively small (8-20%). The SRD%, representing the smallest change that indicates a real improvement for a single subject ranged from 26% to 33% for concentric knee extension, from 39% to 55% for concentric knee flexion, and from 22% to 25% for eccentric knee extension. Conclusion: Isokinetic knee muscle strength can be reliably measured and used to detect real improvements following an intervention for single subjects as well as for groups of subjects with chronic mild to moderate hemiparesis after stroke.
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| 11. |
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| 12. |
- Grote, Fredrik, 1995-, et al.
(författare)
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Phase equilibrium, dynamics and rheology of phospholipid-ethanol mixtures : a combined molecular dynamics, NMR and viscometry study
- 2023
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 25:23, s. 15905-15915
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Tidskriftsartikel (refereegranskat)abstract
- Binary mixtures of ethanol and phospholipids DOPC and DOPE have been investigated in a composition range relevant for topical drug delivery applications. This was done using a combined computer simulation and experimental approach where molecular dynamics simulations of ethanol-lipid mixtures with different compositions were performed. Several key properties including diffusion coefficients, longitudinal relaxation times, and shear viscosity were computed. In addition, diffusion coefficients, viscosities and NMR longitudinal relaxation times were measured experimentally for comparison and in order to validate the results from simulation. Diffusion coefficients and relaxation times obtained from simulations are in good agreement with results from NMR and computed viscosities are in reasonable agreement with viscometry experiments indicating that the simulations provide a realistic description of the ethanol-phospholipid mixtures. Structural changes in the simulated systems were investigated using an analysis based on radial distribution functions. This showed that the structure of ethanol-DOPC mixtures remains essentially unchanged in the investigated concentration range while ethanol-DOPE mixtures undergo structural rearrangements with the tendency for forming small aggregates on the 100 ns time scale consisting of less than 10 lipids. Although our simulations and experiments indicate that no larger aggregates form, they also show that DOPE has stronger aggregation tendency than DOPC. This highlights the importance of the character of the lipid headgroup for lipid aggregation in ethanol and gives new insights into phase equilibrium, dynamics and rheology that could be valuable for the development of advanced topical drug delivery formulations.
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| 13. |
- Holmbäck, Jan, et al.
(författare)
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AKVANO (R) : A Novel Lipid Formulation System for Topical Drug Delivery-In Vitro Studies
- 2022
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:4
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Tidskriftsartikel (refereegranskat)abstract
- A novel formulation technology called AKVANO (R) has been developed with the aim to provide a tuneable and versatile drug delivery system for topical administration. The vehicle is based on a water-free lipid formulation where selected lipids, mainly phospholipids rich in phosphatidylcholine, are dissolved in a volatile solvent, such as ethanol. With the aim of describing the basic properties of the system, the following physicochemical methods were used: viscometry, dynamic light scattering, NMR diffusometry, and atomic force microscopy. AKVANO formulations are non-viscous, with virtually no or very minute aggregates formed, and when applied to the skin, e.g., by spraying, a thin film consisting of lipid bilayer structures is formed. Standardized in vitro microbiological and irritation tests show that AKVANO formulations meet criteria for antibacterial, antifungal, and antiviral activities and, at the same time, are being investigated as a non-irritant to the skin and eye. The ethanol content in AKVANO facilitates incorporation of many active pharmaceutical ingredients (>80 successfully tested) and the phospholipids seem to act as a solubilizer in the formulation. In vitro skin permeation experiments using Strat-M (R) membranes have shown that AKVANO formulations can be designed to alter the penetration of active ingredients by changing the lipid composition.
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| 14. |
- Holmbäck, Jan
(författare)
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Magnetic moments
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents the background, the methodology andsome applications of the utilization of NMR spectroscopy inlipid science. The basic principles of NMR spectroscopy and itspractical implementation for studies of lipids are described. Asystematic review of different lipid classes and theirstructural features is presented. Six applications illustratedifferent utilization of NMR spectroscopy for the use in lipidscience. For example, effect on NMR chemical shifts of solventsystems, control of experimental parameters, combinations ofdifferent 1D and 2D experiments to facilitate assignment ofsignals, the support from other analytical techniques forextensive structural investigations, the use of acetylation asan aid for structural elucidation and use of NMR signals forquantitative determinations are described.
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| 15. |
- Holmbäck, Jan, et al.
(författare)
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Preclinical development of sodium fusidate antibiotic cutaneous spray based on water-free lipid formulation system
- 2022
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- Topical antibiotics are a key component in the management of mild to moderate skin and soft tissue infections. There are, however, concerns about the emerging bacterial resistance against topical antibacterial agents such as fusidic acid, due to the prolonged treatment period of its marketed dosage forms. Improving the efficacy of topical formulations could potentially shorten the treatment period and avoid the resistance growth. To provide a more effective drug delivery, a water-free lipid-based formulation system (AKVANO (R)) which can be applied by spraying, has been developed. In the current paper, different formulations containing sodium fusidate were evaluated for their in vitro skin permeability using artificial skin mimicking membranes and antibacterial properties using ex vivo and in vivo skin wound infection models. The novel formulations containing sodium fusidate showed a much higher skin permeation (up to 60% of nominal amount) than the commercially available Fucidin (R) cream (3%). These formulations also gave a significantly stronger antibacterial effect than Fucidin cream showing a clear dose-response relationship for the sodium fusidate content. A spray product based on the described formulation technology would therefore require a shorter treatment time and thereby lower the risk for the development of bacterial resistance. Spray administration of these formulations provides an even layer on the skin surface from which the solvent quickly evaporates and thereby facilitates a non-touch application where no rubbing is required.
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| 16. |
- Holmbäck, Ulf, et al.
(författare)
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Overweight more prevalent among children than among adolescents
- 2007
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Ingår i: Acta Paediatrica. - : John Wiley & Sons. - 0803-5253 .- 1651-2227. ; 96:4, s. 577-581
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Tidskriftsartikel (refereegranskat)abstract
- Aims To study if there is a change in paediatric overweight/obesity prevalence from 1982 to 2002 in a population with a high proportion of post-graduate education. Design Two samples of children in Uppsala County, Sweden, were compared: children who were 4, 10 and 16 year old in 1982; or 4, 10 and 16 year old in 2002. Mean BMI (in the lowest 10%, middle 50% and highest 10%) and ISO-BMI ('age adjusted BMI') cut-off values were calculated in each age and gender group. Results Using the mean BMI or ISO-BMI cut-off values, the BMI-distribution shifted from 1982 to 2002. More 4- and 10-year-old girls and boys were overweight/obese, although this shift was larger in girls. No shift was seen in the 16-year-olds, only the middle 50% group in the 16-year-old girls had a slight increase of their mean BMI. In the 2002 4-year-old, and both 10-year-old samples, a higher proportion of the girls were overweight/obese compared to the boys, but no difference was seen in the 16-year-old sample. Conclusion Young children, especially girls, have become much more overweight/obese during the past 20 years, despite a high proportion of post-graduate education in the population. The lack of major change in 16-year-olds may suggest a rather recent change in the children's environment/lifestyle.
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| 17. |
- Iadaresta, Francesco, et al.
(författare)
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Chemicals from textiles to skin : an in vitro permeation study of benzothiazole
- 2018
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 25:25, s. 24629-24638
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Tidskriftsartikel (refereegranskat)abstract
- Despite the possible impact on human health, few studies have been conducted to assess the penetration and accumulation of contaminants in the skin after a prolonged contact with textile materials. In previous studies, we have shown that benzothiazole and its derivatives, as well as other potentially hazardous chemicals, often are present as textile contaminants in clothes available on the retail market. Since benzothiazole is a common contaminant in clothes, these can be a possible route for human chemical exposure, both systemic and onto the skin. To investigate this potential exposure, Franz-type and flow-through cells were used for the permeation studies together with a Strat-MA (R) artificial membranes. Experiments were performed using solutions of benzothiazole, as well as contaminated textile samples in the donor chamber. Benzothiazole was demonstrated to penetrate through, as well as being accumulated in the membrane mimicking the skin. After 24 h, up to 62% of benzothiazole was found in the acceptor cell, while up to 37% was found absorbed in the skin mimicking membrane. It also was shown that there was release and permeation from contaminated fabrics. The results indicate that benzothiazole can be released from textile materials, penetrate through the skin, and further enter the human body. This will possibly also apply to other chemical contaminants in textiles, and the results of this study indicate that the presence of these textile contaminants entails potential health risks. A rough risk assessment was made for clothing textiles according to Environmental Protection Agency (EPA) and European regulations for carcinogenic and non-carcinogenic compounds, using literature data for benzothiazole.
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| 18. |
- Iadaresta, Francesco, 1985-
(författare)
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Textile Related Chemicals: Analytical Approaches Towards the Assessment of Human and Environmental Exposures
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The textile manufacturing chain involves an extensive use of chemicals as early as fabric-production. To confer special features to textile materials, more chemicals are required in subsequent steps. Furthermore, potentially harmful substances can end up in clothes as transformation products. Compounds that are not covalently bonded to the fabrics have high probability to be released on the skin or into the environment when the clothes are worn or laundered.In order to remove interfering compounds from solvent extracts of investigated textiles, a cleanup step based on solid phase extraction using graphitic carbon black was developed resulting in effective dye removal. In a pilot screening, nitroanilines were detected up to 0.57 mg/g, which was 2-3 order of magnitude higher than measured quinolines.Human exposure to chemicals can occur through skin contact. Benzothiazole was chosen as model compound for in-vitro experiments. Its permeation was experimentally determined in order to estimate dermal exposure. Carcinogenic and non-carcinogenic risks, associated to wearing t-shirt containing BT, according to international standards, were found to be below the acceptable exposure levels.It has been shown that chemical concentrations decreased during domestic washing. A procedure was developed for enrichment and clean-up of textile related compounds from water samples. The method was applied to three wastewater treatment plant effluents located in Stockholm. Tolyltriazole, 1-benzotriazole, and UV-P were detected within the range of 53-1148 ng/L.Suspect and non-target screening methodology was developed do detect and identify substances in textile materials. The occurrence of thirteen suspect compounds, belonging to quinolines, nitroanilines, benzotriazoles, benzothiazoles and phthalates, was confirmed through suspect analysis approach. Furthermore, using a non-target screening approach, compounds not included in the suspect list such as nitrophenols, organophosphate and acridine were identified.In order to remove interfering compounds from the textile extracts, a cleanup step based on solid phase extraction using graphitic carbon black was developed resulting in effective dye removal. In a pilot screening, nitroanilines were detected up to 0.57 mg/g, which was 2-3 times higher than measured quinolines.Human exposure to chemicals can occur through skin contact. Benzothiazole was chosen as model compound for in-vitro experiments. Its permeation was experimentally determined in order to estimate dermal exposure. Carcinogenic and non-carcinogenic risks, associated to wearing t-shirt containing BT, according to international standards, were found to be below the acceptable exposure levels.It has been shown that chemical concentrations decreased during domestic washing. A procedure was developed for enrichment and clean-up of textile related compounds from water samples. The method was applied to three wastewater treatment plant effluents located in Stockholm. Tolyltriazole, 1-benzotriazole, and UV-P were detected within the range of 53-1148 ng/L. Suspect and non-target screening methodology was developed do detect and identify substances in textile materials. The occurrence of thirteen suspect compounds, belonging to quinolines, nitroanilines, benzotriazoles, benzothiazoles and phthalates, was confirmed through suspect approach. Furthermore, using a non-target screening approach, compounds not included in suspect list such as nitrophenols, organophosphate and acridine were identified.
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| 19. |
- Jahnke, Annika, et al.
(författare)
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Differences between Lipids Extracted from Five Species Are Not Sufficient To Explain Biomagnification of Nonpolar Organic Chemicals
- 2015
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Ingår i: Environmental Science and Technology Letters. - : American Chemical Society (ACS). - 2328-8930. ; 2:7, s. 193-197
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Tidskriftsartikel (refereegranskat)abstract
- Lipids are the major sorptive phase for many organic chemicals that bioaccumulate in foodwebs. However, lipids are usually operationally defined by the extraction protocol. Large differences in sorptive capacities between species would violate assumptions implicit in widely used lipid-normalization procedures and invalidate generic bioaccumulation factors. We extracted lipids from five species from different trophic levels and domains and determined fractions of triglycerides, phospholipids, and cholesterol. We passively dosed the lipids with cyclic volatile methylsiloxanes and chlorobenzenes via headspace from spiked olive oil to determine their sorptive capacities. Lipids from seal blubber and pork bacon solely composed of triglycerides had capacities similar to that of olive oil; lipids from mussels, herring, and guillemot egg had quantifiable fractions of phospholipids and cholesterol and showed capacities reduced by factors of up to 2.3-fold. Generally, the sorptive capacities of the lipids were not elevated relative to the olive oil controls and are unlikely to explain a substantial part of biomagnification.
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| 20. |
- Jaworowski, Å, et al.
(författare)
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Enzyme activities in the tibialis anterior muscle of young moderately active men and women: relationship with body composition, muscle cross-sectional area and fibre type composition.
- 2002
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 176:3, s. 215-225
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were (i) to assess the differences between men and women in maximal activities of selected enzymes of aerobic and anaerobic pathways involved in skeletal muscle energy production, and (ii) to assess the relationships between maximal enzyme activities, body composition, muscle cross-sectional area (CSA) and fibre type composition. Muscle biopsies were obtained from the tibialis anterior (TA) muscle of 15 men and 15 women (age 20-31 years) with comparable physical activity levels. The muscle CSA was determined by magnetic resonance imaging (MRI). Maximal activities of lactate dehydrogenase (LDH), phosphofructokinase (PFK), beta-hydroxyacyl-coenzyme A dehydrogenase (HAD), succinate dehydrogenase (SDH) and citrate synthase (CS), were assayed spectrophotometrically. The proportion, mean area and relative area (proportion x area) of type 1 and type 2 fibres were determined from muscle biopsies prepared for enzyme histochemistry [myofibrillar adenosine triphosphatase (mATPase)]. The men were significantly taller (+6.6%; P < 0.001) and heavier (+19.1%; P < 0.001), had significantly larger muscle CSA (+19.0%; P < 0.001) and significantly larger areas and relative areas of both type 1 and type 2 fibres (+20.5-31.4%; P = 0.007 to P < 0.001). The men had significantly higher maximal enzyme activities than women for LDH (+27.6%; P = 0.007) and PFK (+25.5%; P = 0.003). There were no significant differences between the men and the women in the activities of HAD (+3.6%; ns), CS (+21.1%; P = 0.084) and SDH (+7.6%; ns). There were significant relationships between height and LDH (r = 0.41; P = 0.023), height and PFK (r = 0.41; P = 0.025), weight and LDH (r = 0.45; P = 0.013), and weight and PFK (r = 0.39; P = 0.032). The relationships were significant between the muscle CSA and the activities of LDH (r = 0.61; P < 0.001) and PFK (r = 0.56; P = 0.001), and between the relative area of type 2 fibres and the activities of LDH (r = 0.49; P = 0.006) and PFK (r = 0.42; P = 0.023). There were no significant relationships between HAD, CS and SDH, and height, weight, muscle CSA and fibre type composition, respectively. These data indicate that the higher maximal activities of LDH and PFK in men are related to the height, weight, muscle CSA and the relative area of type 2 fibres, which are all significantly larger in men than women.
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| 21. |
- Miller, Michael, et al.
(författare)
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Voluntary activation and central activation failure in the knee extensors in young women and men
- 2006
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 16:4, s. 274-81
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Tidskriftsartikel (refereegranskat)abstract
- Quadriceps muscle weakness is common after knee injuries. This weakness is caused, in part, by reduced voluntary activation (VA) because of central activation failure (CAF). Superimposed electrical stimulation techniques are used to assess VA and to detect CAF. The aim of this study was to assess VA during knee extension in young healthy women and men, and to evaluate subjective discomfort from the electrical stimulation. The quadriceps muscle in six young healthy women (mean age 22 years) and six young healthy men (mean age 29 years) was stimulated during maximal voluntary contractions using a 100 Hz pulse train. Data were collected from two test sessions separated by 6-8 days and each session comprised of two trials. A visual analog scale for pain (VAS-pain) was used to evaluate subjective discomfort. Overall, young healthy, moderately active men and women did have the ability to fully activate their knee extensors isometrically, but they did not achieve full activation on every trial. In those trials where a CAF was detected, the degree was small (mean less than 2%), and did not vary between the two test sessions. Subjective discomfort was generally moderate and tolerable (mean VAS-pain score 35 mm). These results will assist the clinical assessment of muscle weakness following a knee injury and facilitate the design and evaluation of appropriate rehabilitation interventions.
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| 22. |
- Olsson, Petter, et al.
(författare)
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A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1369, s. 105-115
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection.
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| 23. |
- Olsson, Petter, et al.
(författare)
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Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates
- 2014
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1360, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino- modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material.
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| 24. |
- Olsson, Petter, 1981-
(författare)
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Essentially Lipids : Analytical methods for the characterization of lipid materials
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes analytical methods for chromatographic characterizations of lipids in biological and technical systems.Lipids are a group of compounds with a central role in all known forms of life. In addition to the biological roles, lipids are also components in many products of our daily usage. The application areas include food, pharma, cosmetics, biofuels, etc.Analytical characterization of lipids is challenging since a typical lipid extract often contains several hundred unique compounds which also could vary significantly in chemical properties. Separation is in many cases crucial for identification and quantification of individual lipids and here high performance liquid chromatography (HPLC) is regarded as the technique of first choice today.In the present work, methodologies for both normal phase (NP) and reversed phase (RP) HPLC are presented. The focus has been to develop methods that are fast, have low analytical complexity and are compatible with several detection systems. Cyanopropyl coated silica was evaluated as stationary phase for NP-HPLC with the aim to separate all the lipid classes in common lipid extracts. The analytes were eluted with a binary mobile phase system based on hexane, toluene and methanol which yielded in a total runtime of 30 minutes. In a subsequent study, additional stationary phases for NP-HPLC were evaluated for online sample cleanup of polycyclic aromatic hydrocarbons (PAHs) in lipid matrixes. In the demonstrated methodology for RP-HPLC, a binary system consisting of methanol/water was utilized with phenylpropyl coated silica to elute all tested lipid classes in 30 minutes.The methodologies were compatible with various detection techniques including evaporative light scattering detection (ELSD), charged aerosol detection (CAD) as well as electrospray mass spectrometry (ESI-MS) and were applied to characterize lipid materials of both biological and technical nature.
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| 25. |
- Olsson, Petter, et al.
(författare)
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Separation And Identification Of Lipid Classes By Normal Phase Lc-Esi/Ms/Ms On A Cyanopropyl Column
- 2014
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Ingår i: European Journal of Lipid Science and Technology. - : Wiley. - 1438-7697 .- 1438-9312. ; 116:5, s. 653-658
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Tidskriftsartikel (refereegranskat)abstract
- In order to establish a versatile and convenient method for the analysis of lipids, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was applied to a HPLC separation on a cyanopropyl-bonded stationary phase. A binary gradient mobile phase system consisting of hexane, toluene, methanol and a stable electrospray yielding sodium adduct ions could be used to generate specific product ions in MS/MS mode. By applying the LC/ESI-MS/MS method on an egg yolk sample, 29 different molecular species of phosphatidylethanolamines, phosphatidylcholines, and lysophosphatidylcholines could be detected within 25 min.
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| 26. |
- Olsson, Petter, et al.
(författare)
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Separation of Lipid Classes by HPLC on a Cyanopropyl Column
- 2012
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 47:1, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- A new method for the separation and identification of lipid classes by normal-phase HPLC on a cyanopropyl column is described. The use of a simple binary gradient, with toluene as a component, provided a rapid separation of non-polar as well as phospholipid classes. The inherent small differences in performances between possible non-polar eluent components of the gradient, such as hexane, heptane, and iso-octane, had a pronounced impact on retention times for individual phospholipid classes. Separation of molecular species within a lipid class could also be observed.
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| 27. |
- Porter, MM, et al.
(författare)
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Reliability of concentric ankle dorsiflexion fatigue testing
- 2002
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Ingår i: Canadian Journal of Applied Physiology. - : Canadian Science Publishing. - 1066-7814 .- 1543-2718. ; 27:2, s. 116-127
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to determine the reliability of an isokinetic test for ankle dorsiflexion fatigue on a Biodex dynamometer Young (21 to 32 years), recreationally active men (n = 10) and women (n = 10) performed 50 concentric (60degrees . s(-1)) dorsiflexion contractions, on two different occasions. Total work (TW), losses in work (work fatigue; WF), as well as relative losses in peak torque, an example being "3-3" which compared the first three to last three repetitions, were measured. The intra-class correlation coefficients (ICC2,1) and coefficients of variation (CV), as well as the Bland-Altman plots and analyses showed that the variables using peak torque and TW were more reliable than WF with WF having a CV of 11.3% and the best peak torque variable, 3-3, having a CV of 5.6%. In conclusion, ankle dorsiflexion fatigue can be reliably assessed on a Biodex dynamometer.
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| 28. |
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| 29. |
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