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- Canaider, S., et al.
(author)
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Human Stem Cell Exposure to Developmental Stage Zebrafish Extracts : a Novel Strategy for Tuning Stemness and Senescence Patterning
- 2014
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In: Cell. - 2329-7042. ; 2:5
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Journal article (peer-reviewed)abstract
- Background: Zebrafish exhibits extraordinary ability for tissue regeneration. Despite growing investigations dissecting the molecular underpinning of such regenerative potential, little is known about the possibility to use the chemical inventory of the zebrafishembryo to modulate human stem cell dynamics.Methods: Extracts from zebrafish embryo were collected at different developmental stages, referred to as ZF1, ZF2, ZF3 (early stages), and ZF4, ZF5 (late stages). Human adipose-derived stem cells (hASCs), isolated from microfractured fat tissue obtained with a novel non-enzymatic method (Lipogems), were cultured in absence or presence of each developmental stage extract. Cell viability was assessed by MTT assay. Nuclear morphology was investigated by cell-permeable dye 4’,6-DAPI. Caspase-3 activity was assessed by ELISA. Gene transcription was monitored by real-time PCR.Results: Late developmental stage extracts decreased cell viability and elicited caspase-3 mediated apoptosis. This effect did not involve Bax or Bcl-2 transcription. Conversely, early developmental stage ZF1 did not affect cell viability or apoptosis, albeit increasing Bax/Bcl-2mRNA ratio. ZF1 enhanced transcription of the stemness/pluripotency genes Oct-4, Sox-2and c-Myc. ZF1 also induced the transcription of TERT, encoding the catalytic subunit of telomerase, as well as the gene expression of Bmi-1, a chromatin remodeler acting as a major telomerase-independent repressor of senescence. These transcriptional responses were restricted to the action of early stage factors, since they were not elicited by late developmental stage ZF5.Conclusions: Exposure to early developmental stage zebrafish embryo extracts may enhance stem cell expression of multipotency and activate both telomerase-dependent and -independent antagonists of cell senescence. These outcomes may prove rewarding during prolonged expansion in culture, as it occurs in most cell therapy protocols.
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| 2. |
- Ponsot, Elodie, 1973-, et al.
(author)
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Exercise training in normobaric hypoxia in endurance runners. II. Improvement of mitochondrial properties in skeletal muscle
- 2006
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In: Journal of applied physiology. - Betsheda, USA : American Physiological Society. - 8750-7587 .- 1522-1601. ; 100:4, s. 1249-57
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Journal article (peer-reviewed)abstract
- This study investigates whether adaptations of mitochondrial function accompany the improvement of endurance performance capacity observed in well-trained athletes after an intermittent hypoxic training program. Fifteen endurance-trained athletes performed two weekly training sessions on treadmill at the velocity associated with the second ventilatory threshold (VT2) with inspired O2 fraction = 14.5% [hypoxic group (Hyp), n = 8] or with inspired O2 fraction = 21% [normoxic group (Nor), n = 7], integrated into their usual training, for 6 wk. Before and after training, oxygen uptake (VO2) and speed at VT2, maximal VO2 (VO2 max), and time to exhaustion at velocity of VO2 max (minimal speed associated with VO2 max) were measured, and muscle biopsies of vastus lateralis were harvested. Muscle oxidative capacities and sensitivity of mitochondrial respiration to ADP (Km) were evaluated on permeabilized muscle fibers. Time to exhaustion, VO2 at VT2, and VO2 max were significantly improved in Hyp (+42, +8, and +5%, respectively) but not in Nor. No increase in muscle oxidative capacity was obtained with either training protocol. However, mitochondrial regulation shifted to a more oxidative profile in Hyp only as shown by the increased Km for ADP (Nor: before 476 +/- 63, after 524 +/- 62 microM, not significant; Hyp: before 441 +/- 59, after 694 +/- 51 microM, P < 0.05). Thus including hypoxia sessions into the usual training of athletes qualitatively ameliorates mitochondrial function by increasing the respiratory control by creatine, providing a tighter integration between ATP demand and supply.
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| 3. |
- Ponsot, Elodie, 1973-, et al.
(author)
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Impairment of maximal aerobic power with moderate hypoxia in endurance athletes : do skeletal muscle mitochondria play a role?
- 2010
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In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 298:3, s. R558-R566
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Journal article (peer-reviewed)abstract
- This study investigates the role of central vs. peripheral factors in the limitation of maximal oxygen uptake ((V) over dot O-2max) with moderate hypoxia [inspired fraction (FIO2) = 14.5%]. Fifteen endurance-trained athletes performed maximal cycle incremental tests to assess (V) over dotO(2max), maximal cardiac output ((Q) over dot(max)), and maximal arteriovenous oxygen (a-vO(2)) difference in normoxia and hypoxia. Muscle biopsies of vastus lateralis were taken 1 wk before the cycling tests to evaluate maximal muscle oxidative capacity ((V) over dot(max)) and sensitivity of mitochondrial respiration to ADP (K-m) on permeabilized muscle fibers in situ. Those athletes exhibiting the largest reduction of (V) over dotO(2max) in moderate hypoxia (Severe Loss group: -18 +/- 2%) suffered from significant reductions in Q(max) (-4 +/- 1%) and maximal a-vO(2) difference (-14 +/- 2%). Athletes who well tolerated hypoxia, as attested by a significantly smaller drop of (V) over dotO(2max) with hypoxia (Moderate Loss group: -7 +/- 1%), also display a blunted (Q) over dot(max) (-9 +/- 2%) but, conversely, were able to maintain maximal a-vO(2) difference (+1 +/- 2%). Though (V) over dot(max) was similar in the two experimental groups, the smallest reduction of (V) over dotO(2max) with moderate hypoxia was observed in those athletes presenting the lowest apparent Km for ADP in the presence of creatine (K-m (+) (Cr)). In already-trained athletes with high muscular oxidative capacities, the qualitative, rather than quantitative, aspects of the mitochondrial function may constitute a limiting factor to aerobic ATP turnover when exercising at low FIO2, presumably through the functional coupling between the mitochondrial creatine kinase and ATP production. This study suggests a potential role for peripheral factors, including the alteration of cellular homeostasis in active muscles, in determining the tolerance to hypoxia in maximally exercising endurance-trained athletes.
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