| 1. |
- Moretti, Chiara H., et al.
(författare)
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Dietary nitrite extends lifespan and prevents age-related locomotor decline in the fruit fly
- 2020
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 160, s. 860-870
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Tidskriftsartikel (refereegranskat)abstract
- Aging is associated with decreased nitric oxide (NO) bioavailability and signalling. Boosting of a dietary nitrate nitrite-NO pathway e.g. by ingestion of leafy green vegetables, improves cardiometabolic function, mitochondrial efficiency and reduces oxidative stress in humans and rodents, making dietary nitrate and nitrite an appealing intervention to address age-related disorders. On the other hand, these anions have long been implicated in detrimental health effects of our diet, particularly in formation of carcinogenic nitrosamines.The aim of this study was to assess whether inorganic nitrite affects lifespan in Drosophila melanogaster and investigate possible mechanisms underlying any such effect.In a survival assay, female flies fed a nitrite supplemented diet showed lifespan extension by 9 and 15% with 0.1 and 1 mu M nitrite respectively, with no impact of nitrite on reproductive output. Interestingly, nitrite could also protect female flies from age-dependent locomotor decline, indicating a protective effect on healthspan. NO generation from nitrite involved Drosophila commensal bacteria and was indicated by a fluorescent probe as well as direct measurements of NO gas formation with chemiluminescence.Nutrient sensing pathways such as TOR and sirtuins, have been strongly implicated in lifespan extension. In aged flies, nitrite supplementation significantly downregulated dTOR and upregulated dSir2 gene expression. Total triglycerides and glucose were decreased, a described downstream effect of both TOR and sirtuin pathways.In conclusion, we demonstrate that very low doses of dietary nitrite extend lifespan and favour healthspan in female flies. We propose modulation of nutrient sensing pathways as driving mechanisms for such effects.
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| 2. |
- Lard, Mercy, et al.
(författare)
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Nanowire-Imposed Geometrical Control in Studies of Actomyosin Motor Function
- 2015
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Ingår i: IEEE Transactions on Nanobioscience. - : IEEE. - 1536-1241 .- 1558-2639. ; 14:3, s. 289-297
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Tidskriftsartikel (refereegranskat)abstract
- Recently, molecular motor gliding assays with actin and myosin from muscle have been realized on semiconductor nanowires coated with Al2O3. This opens for unique nanotechnological applications and novel fundamental studies of actomyosin motor function. Here, we provide a comparison of myosin-driven actin filament motility on Al2O3 to both nitrocellulose and trimethylchlorosilane derivatized surfaces. We also show that actomyosin motility on the less than 200 nm wide tips of arrays of Al2O3-coated nanowires can be used to control the number, and density, of myosin-actin attachment points. Results obtained using nanowire arrays with different inter-wire spacing are consistent with the idea that the actin filament sliding velocity is determined both by the total number and the average density of attached myosin heads along the actin filament. Further, the results are consistent with buckling of long myosin-free segments of the filaments as a factor underlying reduced velocity. On the other hand, the findings do not support a mechanistic role in decreasing velocity, of increased nearest neighbor distance between available myosin heads. Our results open up for more advanced studies that may use nanowire-based structures for fundamental investigations of molecular motors, including the possibility to create a nanowire-templated bottom-up assembly of 3D, muscle-like structures.
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| 3. |
- Põlajeva, Jelena, 1983-, et al.
(författare)
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miRNA-21 is developmentally regulated in mouse brain and is co-expressed with SOX2 in glioma
- 2012
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407 .- 1471-2407. ; 12, s. 378-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMicroRNAs (miRNAs) and their role during tumor development have been studied in greatdetail during the last decade, albeit their expression pattern and regulation during normaldevelopment are however not so well established. Previous studies have shown that miRNAsare differentially expressed in solid human tumors. Platelet-derived growth factor (PDGF)signaling is known to be involved in normal development of the brain as well as in malignantprimary brain tumors, gliomas, but the complete mechanism is still lacking. We decided toinvestigate the expression of the oncogenic miR-21 during normal mouse development andglioma, focusing on PDGF signaling as a potential regulator of miR-21.MethodsWe generated mouse glioma using the RCAS/tv-a system for driving PDGF-BB expression ina cell-specific manner. Expression of miR-21 in mouse cell cultures and mouse brain wereassessed using Northern blot analysis and in situ hybridization. Immunohistochemistry andWestern blot analysis were used to investigate SOX2 expression. LNA-modified siRNA wasused for irreversible depletion of miR-21. For inhibition of PDGF signaling Gleevec(imatinib mesylate), Rapamycin and U0126, as well as siRNA were used. Statisticalsignificance was calculated using double-sided unpaired Student´s t-test.ResultsWe identified miR-21 to be highly expressed during embryonic and newborn braindevelopment followed by a gradual decrease until undetectable at postnatal day 7 (P7), thiscorrelated with SOX2 expression. Furthermore, miR-21 and SOX2 showed up-regulation andoverlapping expression pattern in RCAS/tv-a generated mouse brain tumor specimens. Uponirreversible depletion of miR-21 the expression of SOX2 was strongly diminished in bothmouse primary glioma cultures and human glioma cell lines. Interestingly, in normalfibroblasts the expression of miR-21 was induced by PDGF-BB, and inhibition of PDGFsignaling in mouse glioma primary cultures resulted in suppression of miR-21 suggesting thatmiR-21 is indeed regulated by PDGF signaling.ConclusionsOur data show that miR-21 and SOX2 are tightly regulated already during embryogenesisand define a distinct population with putative tumor cell of origin characteristics. We believethat miR-21 is a mediator of PDGF-driven brain tumors, which suggests miR-21 as apromising target for treatment of glioma.
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| 4. |
- Gullstrand, Lennart, et al.
(författare)
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A new method for recording the temporal pattern of stride during treadmill running
- 2009
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; :11, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the reliability of a new infrared light based method (IR40) for recording temporal stride patterns during treadmill running. The IR40 device, emitting a tight web of 40 infrared light beams 10 mm above the treadmill running surface, was compared to a previously validated electro-pneumatic contact shoe (CS) method while nine well-trained athletes ran at 2.8, 3.3, 3.9, 4.4, 5.0, and 5.6 m s−1. Disconnection and reconnection of the IR beams marked the stance phase. The sampling rate was 500 Hz for both methods. The stance phase duration was on average 11.5 (±8.4) ms longer with the IR40 than with the CS depending on earlier touch down (8.3 ± 6.2 ms) and delayed toe off (3.2 ± 5.3 ms) registrations. Significantly different stance phases were recorded between all velocities and for both methods. Thus, despite the fact that the IR40 systematically measured a somewhat longer stance phase duration than CS, the IR40 is nonetheless useful for temporal stride analysis during treadmill running.
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| 5. |
- Halvorsen, Kjartan, et al.
(författare)
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Minimal marker set for center of mass estimation in running
- 2009
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 30:4, s. 552-555
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to study the validity of a recently proposed method [Forsell C, Halvorsen K. A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum. journal of Biomechanics 2009;42(3):361-5] for estimating the trajectory of the whole-body center of mass (CoM) in the case of running at: velocities ranging from 10 to 22 km h(-1). The method gives an approximation to the CoM using the position of fewer markers on the body than the standard method of tracking each segment of the body. Fourteen male athletes participated. A standard method for determining the CoM from a model of 13 segments and using the position of 36 markers was used as reference method. Leave-one-out cross-validation revealed errors that decreased with increasing number of markers used in the approximative method. Starting from four markers, the error in absolute position of the CoM decreased from 15 mm to 3 mm in each direction. For the velocity of the CoM the estimation bias was neglectable, and the random error decreased from 0.15 to 0.05 m s(-1). The inter-subject and intra-subject variability in the estimated model parameters increased with increasing number of markers. The method worked well also when applied to running at velocities outside the range of velocities in the data used to determine the model parameters. The results indicate that a model using 10 markers represents a good trade-off between simplicity and accuracy, but users must take into account requirements of their specific applications.
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| 6. |
- Holmberg, Hans-Christer, et al.
(författare)
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Reliability and validity of a new double poling ergometer for cross-country skiers
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 - 70% higher than that at the flywheel. There was a high test - retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W . kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.
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| 7. |
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| 8. |
- Karlsen, Jon, et al.
(författare)
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Club shaft weight in putting accuracy and perception of swing parameters in golf putting.
- 2007
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Ingår i: Perceptual and Motor Skills. - : SAGE Publications. - 0031-5125 .- 1558-688X. ; 105:1, s. 29-38
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Tidskriftsartikel (refereegranskat)abstract
- This study assessed how shaft weight influenced golf putting accuracy and subjective perception of swing parameters. Three putters of different shaft weight (100, 420, and 610 gm) were tested by 24 club players. Distance and deviation in direction were measured, and subjective ratings of the putters recorded. Subjects hit the ball further with lighter shafts. The mean distance hit was 100.2, 99.3, and 98.1% of the target distance for the normal, medium, and heavy putter shafts, respectively. Subjectively, the medium heavy putter was rated best on "overall feeling" and it was also rated better than the normal on"feeling of stability in the downswing." The heaviest putter was rated as too heavy by 23 of 24 subjects. There were no significant differences between the putter clubs in distance and directional putting accuracy. The major findings are that the golfers putted 2.1% longer with the 100 gm shaft than with the 610 gm shaft and that the perception of overall feeling of the putter club was not related to performance.
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