| 1. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Roller ski rolling resistance and its effects on elite athletes’ performance
- 2009
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Ingår i: Sports Engineering. - Paris : Springer. - 1369-7072 .- 1460-2687. - 9782287990564 - 9782287990557 ; 11:3, s. 143-157
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Tidskriftsartikel (refereegranskat)abstract
- Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes, the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study, the roller skis’ rolling resistance was measured on the ski-treadmill’s surface using a roller ski rolling resistance measurement system specially produced for this purpose. The study investigated the influence of significant changes in rolling resistance on physiological variables. The results showed that during submaximal exercise, power, oxygen uptake, heart rate and blood lactate were significantly changed by different rolling resistances, while there were no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed by different rolling resistances and this occurred without significant changes in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion were insignificant or small.
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| 2. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Roller ski rolling resistance and its effects on elite athletes’ performance
- 2008
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Ingår i: ENGINEERING OF SPORT 7, VOL 2. - 9782287094125 ; , s. 393-400
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Konferensbidrag (refereegranskat)abstract
- Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study the roller skis’ rolling resistance has been measured using equipment on the ski-treadmill. The study investigates the influence of significant changes in rolling resistance on physiological variables. The results show that during submaximal exercise, heart rate, blood lactate, power and oxygen uptake are significantly changed by different rolling resistances, while there are no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests show that time to exhaustion is significantly changed by different rolling resistances and this occurred without significant changes in maximal oxygen uptake and heart rate, and the influence on maximal power and ratings of perceived exertion were insignificant or small.
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| 3. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Work economy of amateur and elite cross-country skiers during treadmill roller skiing
- 2009
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Ingår i: 4th Asia Pacific Congress on Sports Technology, APCST2009. - 9781921426384
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Konferensbidrag (refereegranskat)abstract
- This study focused on the work economy of cross-country skiers during treadmill roller skiing in the perspectives; skill, age and gender. The study was investigating the external power output from elevating the transported mass against gravity and overcoming the roller skis rolling resistance, and the internal power from measured oxygen uptake and energy consumption. The roller skis rolling resistance was measured with a fixture on the ski-treadmill and the results showed a significant correlation between normal force and rolling resistance. The results also showed that it was only the amateur skiers who significantly differed in work economy among the five studied groups.
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| 4. |
- Astorga, Jeanette, 1976, et al.
(författare)
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Hedgehog induction of murine vasculogenesis is mediated by Foxf1 and Bmp4
- 2007
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Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 134:20, s. 3753-61
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Tidskriftsartikel (refereegranskat)abstract
- The first vasculature of the developing vertebrate embryo forms by assembly of endothelial cells into simple tubes from clusters of mesodermal angioblasts. Maturation of this vasculature involves remodeling, pruning and investment with mural cells. Hedgehog proteins are part of the instructive endodermal signal that triggers the assembly of the first primitive vessels in the mesoderm. We used a combination of genetic and in vitro culture methods to investigate the role of hedgehogs and their targets in murine extraembryonic vasculogenesis. We show that Bmps, in particular Bmp4, are crucial for vascular tube formation, that Bmp4 expression in extraembryonic tissues requires the forkhead transcription factor Foxf1 and that the role of hedgehog proteins in this process is to activate Foxf1 expression in the mesoderm. We show in the allantois that genetic disruption of hedgehog signaling (Smo(-/-)) has no effect on Foxf1 expression, and neither Bmp4 expression nor vasculogenesis are disturbed. By contrast, targeted inactivation of Foxf1 leads to loss of allantoic Bmp4 and vasculature. In vitro, the avascular Foxf1(-/-) phenotype can be rescued by exogenous Bmp4, and vasculogenesis in wild-type tissue can be blocked by the Bmp antagonist noggin. Hedgehogs are required for activation of Foxf1, Bmp4 expression and vasculogenesis in the yolk sac. However, vasculogenesis in Smo(-/-) yolk sacs can be rescued by exogenous Bmp4, consistent with the notion that the role of hedgehog signaling in primary vascular tube formation is as an activator of Bmp4, via Foxf1.
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| 5. |
- Blixt, Åsa, 1960, et al.
(författare)
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Foxe3 is required for morphogenesis and differentiation of the anterior segment of the eye and is sensitive to Pax6 gene dosage.
- 2007
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Ingår i: Developmental biology. - : Elsevier BV. - 0012-1606. ; 302:1, s. 218-29
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Tidskriftsartikel (refereegranskat)abstract
- The dysgenetic lens (dyl) mouse mutant has mutations in Foxe3, which inactivate DNA binding by the encoded forkhead transcription factor. Here we confirm, by targeted inactivation, that Foxe3 mutations are responsible for the dyl phenotype, which include loss of lens epithelium; a small, cataractic lens; and failure of the lens to detach from the surface ectoderm. In contrast to a recent report of targeted Foxe3, we found no phenotypic difference between dyl and Foxe3(-/-) mutants when congenic strains were compared, and thus nothing that argues against Foxe3(dyl) being a null allele. In addition to the lens, most tissues of the anterior segment-iris, cornea, ciliary body and trabecular meshwork-are malformed or show differentiation defects. Many of these abnormalities, such as irido-corneal and irido-lenticular adherences, are present in a less severe form in mice heterozygous for the Foxe3 mutation, in spite of these having an intact lens epithelium. Early Foxe3 expression is highly sensitive to a halved Pax6 gene dosage and there is a striking phenotypic similarity between Pax6 and Foxe3 mutants. We therefore propose that many of the ocular malformations associated with Pax6 haploinsufficiency are consequences of a reduced expression of Foxe3.
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| 6. |
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| 7. |
- Hedström, Erik, et al.
(författare)
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Peak CKMB and cTnT accurately estimates myocardial infarct size after reperfusion
- 2007
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Ingår i: Scand Cardiovasc J.. - : Informa UK Limited. ; 41:1, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To find the time-to-peak for creatine kinase MB(mass) (CKMB) and cardiac troponin T (cTnT) after acute reperfusion, to compare peak and cumulative values to estimate infarct size (IS), and to evaluate clinical routine sampling for assessment of IS. DESIGN: Acute primary percutaneous coronary intervention (PCI) was performed in 38 patients with first-time myocardial infarction. In 21 patients, CKMB and cTnT were acquired before PCI and at 1.5, 3, 6, 12, 18, 24, and 48 hours thereafter. In 17 patients, clinical routine samples were acquired at arrival, and at 10 and 20 h. IS was assessed by delayed contrast-enhanced MRI (DE-MRI). RESULTS: Time-to-peak was 7.6+/-3.6 h for CKMB and 8.1+/-3.4 h for cTnT. Peak values correlated strongly to cumulative values (r(s)=0.97-0.98) as well as to DE-MRI (r(s)=0.8-0.82). Clinical routine sampling showed lower rs values (0.47-0.60). CONCLUSIONS: Peak values are likely captured if CKMB and cTnT are acquired at 3, 6, and 12 h after acute PCI. These peak values can be used to estimate myocardial infarct size after acute PCI
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| 8. |
- Jakobsen, J. S., et al.
(författare)
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Temporal ChIP-on-chip reveals Biniou as a universal regulator of the visceral muscle transcriptional network
- 2007
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Ingår i: Genes Dev. - : Cold Spring Harbor Laboratory. - 0890-9369. ; 21:19, s. 2448-60
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Tidskriftsartikel (refereegranskat)abstract
- Smooth muscle plays a prominent role in many fundamental processes and diseases, yet our understanding of the transcriptional network regulating its development is very limited. The FoxF transcription factors are essential for visceral smooth muscle development in diverse species, although their direct regulatory role remains elusive. We present a transcriptional map of Biniou (a FoxF transcription factor) and Bagpipe (an Nkx factor) activity, as a first step to deciphering the developmental program regulating Drosophila visceral muscle development. A time course of chromatin immunoprecipitatation followed by microarray analysis (ChIP-on-chip) experiments and expression profiling of mutant embryos reveal a dynamic map of in vivo bound enhancers and direct target genes. While Biniou is broadly expressed, it regulates enhancers driving temporally and spatially restricted expression. In vivo reporter assays indicate that the timing of Biniou binding is a key trigger for the time span of enhancer activity. Although bagpipe and biniou mutants phenocopy each other, their regulatory potential is quite different. This network architecture was not apparent from genetic studies, and highlights Biniou as a universal regulator in all visceral muscle, regardless of its developmental origin or subsequent function. The regulatory connection of a number of Biniou target genes is conserved in mice, suggesting an ancient wiring of this developmental program.
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| 9. |
- Landgren, Henrik, 1978, et al.
(författare)
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Persistent FoxE3 expression blocks cytoskeletal remodeling and organelle degradation during lens fiber differentiation.
- 2008
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Ingår i: Investigative ophthalmology & visual science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783 .- 0146-0404. ; 49:10, s. 4269-77
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The anterior hemisphere of the lens is covered by an epithelial monolayer that acts as the stem cell population for lens fiber progenitors. Foxe3, a forkhead transcription factor, is essential for proliferation and survival of the epithelial cells, and cessation of Foxe3 expression at the lens equator coincides with the cell cycle arrest that marks initiation of fiber differentiation. In this study, the consequences of persistent Foxe3 expression during fiber differentiation was investigated. METHODS: The alpha-A-crystallin (Cryaa) promoter was used to drive transgenic expression of Foxe3 in murine differentiating lens fibers. RESULTS: Transgenic mice have a dramatically disturbed lens histology and grave cataracts. Microarray transcript profiling showed an increase of mRNAs normally enriched in epithelial cells, consistent with an epithelialization of the transgenic fibers. Some aspects of fiber differentiation were unaffected, such as the expression of alpha- and beta-crystallins and aquaporins, whereas cytoskeletal remodeling, cell adhesion, organelle degradation, and antimitotic signaling were compromised. CONCLUSIONS: Proper inactivation of FoxE3 expression at the lens equator is important for many aspects of fiber differentiation, and persistent expression leads to a partial epithelialization of fiber cells, with severe consequences for lens function.
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| 10. |
- Melnick, M., et al.
(författare)
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Meckel's cartilage differentiation is dependent on hedgehog signaling
- 2005
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Ingår i: Cells Tissues Organs. - : S. Karger AG. - 1422-6405 .- 1422-6421. ; 179:4, s. 146-157
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Tidskriftsartikel (refereegranskat)abstract
- The hedgehog (Hh) signaling pathway has been shown to be essential for craniofacial development. Although mandibular arch derivatives are largely absent in Shh null mice, little is known about the role of Hh signaling during Meckel's cartilage development per se. Mandible development is dependent on the morphogenesis of Meckel's cartilage, which then serves as a template for subsequent skeletal differentiation. In this study, we examine the biological function of Hh signaling during Meckel's cartilage development in vivo and in vitro. E13.5 Shh null mice present a small mesenchymal condensation in the region of a presumptive Meckel's cartilage in the hypoplastic mandibular arch. By E15.5, the Shh mutant exhibits a mere remnant of the mandibular arch, without evidence of Meckel's cartilage differentiation. Further, wild-type embryonic (E11 or E12) mandibular explants cultured for up to 5 days in the presence of cyclopamine, a steroidal alkaloid that specifically disrupts the Hh signaling pathway, exhibit a stage-dependent inhibition of Meckel's cartilage chondroblast differentiation to mature chondrocytes. This phenotype can be rescued by exogenous FGF8, a downstream effector of Hh signaling. Taken together, our results indicate that the Hh signaling pathway is critical to Meckel's cartilage ontogenesis and the rate of chondrogenesis, but not to initial primordium formation. The reliance on Hh signaling is stage dependent. Copyright (C) 2005 S. Karger AG, Basel.
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