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21.
R Moriggi Jr HS Di Mauro SC Dias JM Matos MB Urtado NF Camar?o IV Sousa Neto DC Nascimento RA Tibana CO Assump??o J Prestes CB Urtado 《Biology of sport / Institute of Sport》2015,32(4):289-294
Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances. 相似文献
22.
JI Priego AG Lucas-Cuevas I Aparicio JV Giménez JM Cortell-Tormo P Pérez-Soriano 《Biology of sport / Institute of Sport》2015,32(3):219-223
The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners. 相似文献
23.
Evolution has no foresight, but produces ad hoc solutions by tinkering with available variation. A new study demonstrates how evolution nevertheless prepares organisms for the future by increasing their evolvability. 相似文献
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25.
van Wyk L van der Marel J Schuerwegh AJ Schouffoer AA Voskuyl AE Huizinga TW Bianchi DW Scherjon SA 《Arthritis research & therapy》2011,13(6):R183
Introduction
Studies have shown that fetal progenitor cells persist in maternal blood or bone marrow for more than 30 years after delivery. Increased trafficking of fetal cells occurs during pregnancy complications, such as hypertension, preeclampsia, miscarriage and intra-uterine growth restriction (IUGR). Women with these pregnancy complications are significantly more often HLA-class II compatible with their spouses. Women who later develop scleroderma also give birth to an HLA-class II child more often. From these prior studies we hypothesized that preeclampsia and other pregnancy complications could be associated with increased levels of fetal cell trafficking, and later be involved in the development of scleroderma. 相似文献26.
Suurmond J Dorjée AL Boon MR Knol EF Huizinga TW Toes RE Schuerwegh AJ 《Arthritis research & therapy》2011,13(5):R150
Introduction
Mast cells have been implicated to play a functional role in arthritis, especially in autoantibody-positive disease. Among the cytokines involved in rheumatoid arthritis (RA), IL-17 is an important inflammatory mediator. Recent data suggest that the synovial mast cell is a main producer of IL-17, although T cells have also been implicated as prominent IL-17 producers as well. We aimed to identify IL-17 expression by mast cells and T cells in synovium of arthritis patients. 相似文献27.
Stanislav Isayenkov Jean-Charles Isner Frans JM Maathuis 《Plant signaling & behavior》2011,6(8):1201-1204
Potassium (K) is one of the major nutrients that is essential for plant growth and development. The majority of cellular K+ resides in the vacuole and tonoplast K+ channels of the TPK (Two Pore K) family are main players in cellular K+ homeostasis. All TPK channels were previously reported to be expressed in the tonoplast of the large central lytic vacuole (LV) except for one isoform in Arabidopsis that resides in the plasma membrane. However, plant cells often contain more than one type of vacuole that coexist in the same cell. We recently showed that two TPK isoforms (OsTPKa and OsTPKb) from Oryza sativa localize to different vacuoles with OsTPKa predominantly found in the LV tonoplast and OsTPKb primarily in smaller compartments that resemble small vacuoles (SVs). Our study further revealed that it is the C-terminal domain that determines differential targeting of OsTPKa and OsTPKb. Three C-terminal amino acids were particularly relevant for targeting TPKs to their respective endomembranes. In this addendum we further evaluate how the different localization of TPKa and TPKb impact on their physiological role and how TPKs provide a potential tool to study the physiology of different types of vacuole.Key words: TPK channels, small vacuoles, vacuolar targeting, potassiumThe roles of plant vacuolar K+ channels are diverse and include potassium homeostasis, turgor regulation and responses to abiotic stress. Vacuolar K+-selective channels belong to two-pore K+ (TPK) channel families which have been found in genomes of many plant species such as Arabidopsis, poplar, Physcomitrella, Eucalyptus, barley, potato, rice and tobacco (Fig. 1). TPKs have structural similarity to mammalian “tandem P domain” channels with a secondary structure that contains four transmembrane domains and two pore regions (Fig. 2).1–5 TPK channels have pore regions with a GYGD signature that endows K+ selectivity and a variable number of Ca2+ binding EF domains in the C terminus.3–8 One of the best characterized members of the TPK family is AtTPK1 from Arabidopsis thaliana. AtTPK1 activity is voltage independent but sensitive to cytosolic Ca2+, cytosolic pH and N-terminal phosphorylation by 14-3-3 proteins.5,6,8,9 In Arabidopsis, AtTPK1 expresses in the large lytic vacuole (LV) and plays roles in cellular K+ homeostasis, K+-release during stomatal closure and seed germination.4,5 Other members of the Arabidopsis TPK family (AtTPK2, AtTPK3, AtTPK5) have been shown to localize to the LV but also showed some expression in smaller, vesicle-like, compartments.4 However, none of these isoforms appears to form functional channels in planta although our experiments with heterologous expression of AtTPK3 and AtTPK5 in the K+ uptake deficient E. coli LB2003 demonstrates complementation of bacterial growth phenotype (Isayenkov S, et al. unpublished results). Equally intriguing, is the plasma membrane localization of the Arabidopsis TPK4 isoform, in spite of its sequence being very similar to that of other TPKs.10Open in a separate windowFigure 1Phylogenetic tree of plant TPKs. The three main clusters of TPKs comprise: Cluster 1 with AtTPK1-like channels; Cluster 2 with AtTPK3/TPK5-like channels; Cluster 3 with barley HvTPKb. Bootstrap analysis was performed using ‘Molecular Evolutionary Genetics Analysis, MEGA4’ software available at www.megasoftware.net/mega4/megaOpen in a separate windowFigure 2Two-pore potassium channel secondary structure. TPK channels comprise four transmembrane domains (1–4) and two pore regions (P) per subunit. Functional channels are formed from two subunits. In most TPKs, both P regions contain a K+ selectivity signature, GYGD. However, the tobacco NtTPKa isoform has different motifs in the second P domain. In the N terminal region, TPKs have a 14-3-3 binding domain that impact on channel activity, with the binding of 14-3-3 protein leading to channel activation. C-termini of TPKs show a varying number of putative Ca2+ binding “EF hands” which may vary from zero to two. 相似文献
28.
Salverda ML Dellus E Gorter FA Debets AJ van der Oost J Hoekstra RF Tawfik DS de Visser JA 《PLoS genetics》2011,7(3):e1001321
Whether evolution is erratic due to random historical details, or is repeatedly directed along similar paths by certain constraints, remains unclear. Epistasis (i.e. non-additive interaction between mutations that affect fitness) is a mechanism that can contribute to both scenarios. Epistasis can constrain the type and order of selected mutations, but it can also make adaptive trajectories contingent upon the first random substitution. This effect is particularly strong under sign epistasis, when the sign of the fitness effects of a mutation depends on its genetic background. In the current study, we examine how epistatic interactions between mutations determine alternative evolutionary pathways, using in vitro evolution of the antibiotic resistance enzyme TEM-1 β-lactamase. First, we describe the diversity of adaptive pathways among replicate lines during evolution for resistance to a novel antibiotic (cefotaxime). Consistent with the prediction of epistatic constraints, most lines increased resistance by acquiring three mutations in a fixed order. However, a few lines deviated from this pattern. Next, to test whether negative interactions between alternative initial substitutions drive this divergence, alleles containing initial substitutions from the deviating lines were evolved under identical conditions. Indeed, these alternative initial substitutions consistently led to lower adaptive peaks, involving more and other substitutions than those observed in the common pathway. We found that a combination of decreased enzymatic activity and lower folding cooperativity underlies negative sign epistasis in the clash between key mutations in the common and deviating lines (Gly238Ser and Arg164Ser, respectively). Our results demonstrate that epistasis contributes to contingency in protein evolution by amplifying the selective consequences of random mutations. 相似文献
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AB Chang NC Cox J Purcell JM Marchant PJ Lewindon GJ Cleghorn LC Ee GD Withers MK Patrick J Faoagali 《Respiratory research》2005,6(1):1-5