Shear stress-induced angiogenesis in mouse muscle is independent of the vasodilator mechanism and quickly reversible.

Aim: Is modulation of skeletal muscle capillary supply by altering blood flow due to a presumptive shear stress response per se, or dependent on the vasodilator mechanism? Methods: The response to four different vasodilators, and cotreatment with blockers of NO and prostaglandin synthesis, was compared. Femoral artery blood flow was correlated with capillary-to-fibre ratio (C:F) and protein levels of putative angiogenic compounds. Results: All vasodilators induced a similar increase in blood flow after 14 days, with a similar effect on C:F (1.62 ± 0.05, 1.60 ± 0.01, 1.57 ± 0.06, 1.57 ± 0.07, respectively, all P < 0.05 vs. control 1.20 ± 0.01). Concomitant inhibitors revealed differential effects on blood flow and angiogenesis, demonstrating that a similar response may have different signalling origins. The time course of this response with the most commonly used vasodilator, prazosin, showed that blood flow increased from 0.40 mL min−1 to 0.61 mL min−1 by 28 days (P < 0.05), dropped within 1 week after the cessation of treatment (0.54 mL min−1; P < 0.05) and returned to control levels by 6 weeks. In parallel with FBF, capillary rarefaction began within 1 week (P < 0.05), giving C:F values similar to control by 2 weeks. Of the dominant signalling pathways, prazosin decreased muscle VEGF, but increased its cognate receptor Flk-1 (both P < 0.01); levels of eNOS varied with blood flow (P < 0.05), and Ang-1 initially increased, while its receptor Tie-2 was unchanged, with only modest changes in the antiangiogenic factor TSP-1. Conclusion: Hyperaemia-induced angiogenesis, likely in response to elevated shear stress, is independent of the vasodilator involved, with a rapid induction and quick regression following the stimulus withdrawal

“WORK-TO-WORK” EXERCISE SLOWS PULMONARY OXYGEN UPTAKE KINETICS, DECREASES CRITICAL POWER, AND INCREASES W’ DURING SUPINE CYCLING

We have previously demonstrated that the phase II time constant of pulmonary oxygen uptake kinetics (τ_V ̇ O2) is an independent determinant of critical power (CP) when O2 availability is not limiting, i.e. during upright cycle exercise in young, healthy individuals. Whether this causative relationship remains when O2 availability is impaired remains unknown. During supine exercise, which causes an O2 availability limitation during the exercise transition, we therefore determined the impact of a raised baseline work rate on τ_V ̇ O2 and CP. CP, τ_V ̇ O2, and muscle oxygenation status (the latter via near-infrared spectroscopy) were determined via four severe-intensity constant-power exercise tests completed in two conditions: 1) with exercise initiated from an unloaded cycling baseline (U→S), and 2) with exercise initiated from a moderate-intensity baseline work rate of 90% of the gas exchange threshold (M→S). In M→S, critical power was lower (U→S = 146 ± 39 W, vs. M→S = 132 ± 33 W, P = 0.023) and τ_V ̇ O2 was greater (U→S = 45 ± 16 s, vs. M→S = 69 ± 129 s, P = 0.001) when compared to U→S. There was no difference in tissue oxyhaemoglobin concentration ([HbO2 + MbO2]) at baseline or during exercise. The concomitant increase in τ_V ̇ O2 and reduction in CP during M→S compared to U→S shows for the first time that τ_V ̇ O2 is an independent determinant of CP in conditions where O2 availability is limiting

Low-level laser irradiation promotes the recovery of atrophied gastrocnemius skeletal muscle in rats.

Low-level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight-week-old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga-Al-As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5-bromo-2-deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU-positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.The definitive version is available at www.blackwell-synergy.com and www.expphysiol.org

Education of a two-year-old child in kindergarten and child group

Bakalářská práce se zabývá problematikou edukace dvouletých dětí v zařízeních péče o děti do tří let, především v mateřských školách a dětských skupinách. V teoretické části jsou vysvětleny hlavní pojmy a témata. Popsána jsou zařízení péče o děti do tří let, detailněji jsou charakterizovány dětské skupiny a mateřské školy, včetně jejich legislativního vymezení. Dále je přiblížen vývoj dítěte do tří let, přístupy k edukaci dvouletých dětí v zahraničí, možné problematické aspekty edukace dvouletých dětí a též metodická doporučení pro práci s dvouletými dětmi. V praktické části je s využitím dvou případových studií popsána edukace dvouletých dětí v mateřské škole a dětské skupině. Cílem výzkumu bylo analyzovat podmínky a způsob práce s dvouletými dětmi v mateřské škole a dětské skupině. V mateřských školách je realizována s dvouletými dětmi ve větší míře pedagogická práce, v dětské skupině je pozornost věnována především potřebám dětí, skupiny zajišťují spíše hlídání dětí, obohacené o vhodné aktivity s dvouletými dětmi. KLÍČOVÁ SLOVA edukace, dvouleté dítě, mateřská škola, dětská skupina, učitelka, chůva, dítě v raném věku, péče o dítě mimo rodinu ABSTRACT The bachelor thesis deals with the issue of education of two-year-old children in care facilities for children under three years, especially in..

Education of a two-year-old child in kindergarten and child group

Bakalářská práce se zabývá problematikou edukace dvouletých dětí v zařízeních péče o děti do tří let, především v mateřských školách a dětských skupinách. V teoretické části jsou vysvětleny hlavní pojmy a témata. Popsána jsou zařízení péče o děti do tří let, detailněji jsou charakterizovány dětské skupiny a mateřské školy, včetně jejich legislativního vymezení. Dále je přiblížen vývoj dítěte do tří let, přístupy k edukaci dvouletých dětí v zahraničí, možné problematické aspekty edukace dvouletých dětí a též metodická doporučení pro práci s dvouletými dětmi. V praktické části je s využitím dvou případových studií popsána edukace dvouletých dětí v mateřské škole a dětské skupině. Cílem výzkumu bylo analyzovat podmínky a způsob práce s dvouletými dětmi v mateřské škole a dětské skupině. V mateřských školách je realizována s dvouletými dětmi ve větší míře pedagogická práce, v dětské skupině je pozornost věnována především potřebám dětí, skupiny zajišťují spíše hlídání dětí, obohacené o vhodné aktivity s dvouletými dětmi. KLÍČOVÁ SLOVA edukace, dvouleté dítě, mateřská škola, dětská skupina, učitelka, chůva, dítě v raném věku, péče o dítě mimo rodinu ABSTRACT The bachelor thesis deals with the issue of education of two-year-old children in care facilities for children under three years, especially in...Katedra preprimární a primární pedagogikyFaculty of EducationPedagogická fakult

Attenuation of changes in capillary fine structure and leukocyte adhesion improves muscle performance following chronic ischaemia in rats

Acute ischaemia–reperfusion disrupts capillary fine structure and increases leukocyte adhesion in postcapillary venules. We determined whether chronic muscle ischaemia has similar consequences, and whether it is possible to ameliorate its effect on muscle performance. Following ischaemia (unilateral ligation, common iliac artery) rat hindlimb muscles were examined without other intervention or following treatment with an xanthine oxidase inhibitor (allopurinol), a Na+/H+ exchange blocker (amiloride), or an oxygen free radical scavenger (vitamin E). No significant leukocyte adhesion or rolling, nor changes in capillary fine structure were observed 3 days postsurgery, when limb use was limited. However, leukocyte rolling and adhesion almost trebled by 7 days (P < 0.001), when normal gait was largely restored. Capillary fine structure was disturbed over a similar time course, e.g. relative endothelial volume (control 46%, 7 days 61%; P < 0.05), that resolved by 5 weeks. Where activity was increased by mild electrical stimulation 3 days after ligation muscles showed enhanced capillary swelling (endothelial volume 66%versus 50%, P < 0.005), but improved fatigue index (52%versus 16%, P < 0.001) as a result of greater blood flow. Muscle fatigue after ligation was related to the extent of contraction-induced hyperaemia (R2= 0.725), but not capillary swelling. Amiloride, and to a lesser extent allopurinol but not vitamin E, significantly decreased leukocyte rolling and adhesion, as well as capillary endothelial swelling. We conclude that increased activity of ischaemic muscles on recovery is likely to accentuate acidosis accompanying changes in microcirculation and contribute to enhanced muscle fatigue, whereas formation of oxygen free radicals may be attenuated by endogenous protective mechanisms