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排序方式: 共有291条查询结果,搜索用时 171 毫秒
211.
D Bellar A Hatchett LW Judge ME Breaux L Marcus 《Biology of sport / Institute of Sport》2015,32(4):315-320
CrossFit is becoming increasingly popular as a method to increase fitness and as a competitive sport in both the Unites States and Europe. However, little research on this mode of exercise has been performed to date. The purpose of the present investigation involving experienced CrossFit athletes and naïve healthy young men was to investigate the relationship of aerobic capacity and anaerobic power to performance in two representative CrossFit workouts: the first workout was 12 minutes in duration, and the second was based on the total time to complete the prescribed exercise. The participants were 32 healthy adult males, who were either naïve to CrossFit exercise or had competed in CrossFit competitions. Linear regression was undertaken to predict performance on the first workout (time) with age, group (naïve or CrossFit athlete), VO2max and anaerobic power, which were all significant predictors (p < 0.05) in the model. The second workout (repetitions), when examined similarly using regression, only resulted in CrossFit experience as a significant predictor (p < 0.05). The results of the study suggest that a history of participation in CrossFit competition is a key component of performance in CrossFit workouts which are representative of those performed in CrossFit, and that, in at least one these workouts, aerobic capacity and anaerobic power are associated with success. 相似文献
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214.
The 67-kDa laminin receptor originated from a ribosomal protein that acquired a dual function during evolution 总被引:8,自引:0,他引:8
Ardini E; Pesole G; Tagliabue E; Magnifico A; Castronovo V; Sobel ME; Colnaghi MI; Menard S 《Molecular biology and evolution》1998,15(8):1017-1025
The 67-kDa laminin receptor (67LR) is a nonintegrin cell surface receptor
that mediates high-affinity interactions between cells and laminin.
Overexpression of this protein in tumor cells has been related to tumor
invasion and metastasis. Thus far, only a full-length gene encoding a
37-kDa precursor protein (37LRP) has been isolated. The finding that the
cDNA for the 37LRP is virtually identical to a cDNA encoding the ribosomal
protein p40 has suggested that 37LRP is actually a component of the
translational machinery, with no laminin-binding activity. On the other
hand, a peptide of 20 amino acids deduced from the sequence of 37LR/p40 was
shown to exhibit high laminin-binding activity. The evolutionary
relationship between 23 sequences of 37LRP/p40 proteins was analyzed. This
phylogenetic analysis indicated that all of the protein sequences derive
from orthologous genes and that the 37LRP is indeed a ribosomal protein
that acquired the novel function of laminin receptor during evolution. The
evolutionary analysis of the sequence identified as the laminin-binding
site in the human protein suggested that the acquisition of the
laminin-binding capability is linked to the palindromic sequence LMWWML,
which appeared during evolution concomitantly with laminin.
相似文献
215.
Secondary ion mass spectrometry (SIMS) microscopy, a mass spectrometry method designed in the 1960s, offers new analytical capabilities, high sensitivity (ppm to ppb region), high specificity and improved lateral resolution, thus facilitating insight into many physiological and biomedical questions. Apart from the sample preparation and the physical characteristics of the detection, the biological model must also be considered. SIMS analysis of diffusible ions and molecules requires strict cryogenic procedures which always begin by a flash-freeze fixation. Cellular integrity can be checked by mapping the major element distributions since intra and extracellular ions are redistributed only in damaged cells. Cryofixing may be followed either by a freeze-fracture methodology or by cryoembedding and dry-cutting. Chemical sample preparation is only used for ions or molecules bound to fixed cell structures. The use of scanning procedures ameliorates the lateral resolution and chromosome imaging has been reported with probe size of below 50nm. Absolute quantification can be derived for embedded specimen by using internal references included in tissue equivalent resins. The sensitivity is limited by the ionization yield of the tag element and may be further impaired when working at high mass resolution (≥5000) to eliminate interfering cluster ions. SIMS drug mapping is usually performed after in vitro administration of a molecule to cell culture systems. Drug detection is accomplished indirectly by detecting a tag isotope naturally present or introduced by labelling, mainly with halogens,15N and14C. Molecular imaging with TOF-SIMS is an appealing alternative especially for heavier compounds. We stress some biological problems through a critical review of published SIMS drug studies. SIMS proved useful in assessing the targeting specificity of nuclear medicine pharmaceutics, even after in vivo administration. The first microscopic evidence of a thionamide induced follicular blockade of the iodine organification process is presented in a human sample. 相似文献
216.
1. Antlions are opportunistic trap building predators that cannot control prey encounter. Their trap should ideally retain a great diversity of prey. However, building a single trap that captures many prey with varying characteristics can be challenging. 2. A series of five different ant species ranging from thin to large, of sizes ranging from 2.75 to 6.5 mm, and a mean weight ranging from 0.54 to 6.00 mg were offered in a random succession to antlions. The state of satiation of the antlions was controlled, and their mass and the depth of their pit were recorded. The reaction of antlion to the prey, the probability of capture as well as the time to escape were recorded. 3. The probability of an antlion reaction is an increasing function of the pit depth and a decreasing function of antlion mass. The probability of capture is highest for intermediate prey mass and is an increasing function of pit depth. The time to escape is a declining function of prey mass and an increasing function of pit depth. 4. There is an upper limit to prey mass given that large prey escape out of the pit. There is a lower limit to prey mass given the difficulty to apprehend the smallest, thin species. Consequently, there is a range of prey mass, corresponding to a medium‐sized ant of 2 mg, for which the pit functions best. The physics of insect locomotion on sandy slopes was identified as the key to understanding the functioning of antlion pits. 相似文献
217.
218.
Reyhan Yaka Igor Mapelli Damla Kaptan Ayça Doğu Maciej Chyleński Ömür Dilek Erdal Dilek Koptekin Kıvılcım Başak Vural Alex Bayliss Camilla Mazzucato Evrim Fer Sevim Seda Çokoğlu Vendela Kempe Lagerholm Maja Krzewińska Cansu Karamurat Hasan Can Gemici Arda Sevkar Nihan Dilşad Dağtaş Mehmet Somel 《Current biology : CB》2021,31(11):2455-2468.e18
219.
Boris Musset Susan ME Smith Sindhu Rajan Vladimir V Cherny Deri Morgan Thomas E DeCoursey 《Channels (Austin, Tex.)》2010,4(4):260-265
The voltage-gated proton channel exists as a dimer, although each protomer has a separate conduction pathway, and when forced to exist as a monomer, most major functions are retained. However, the proton channel protomers appear to interact during gating. Proton channel dimerization is thought to result mainly from coiled-coil interaction of the intracellular C-termini. Several types of evidence are discussed that suggest that the dimer conformation may not be static, but is dynamic and can sample different orientations. Zn2+ appears to link the protomers in an orientation from which the channel(s) cannot open. A tandem WT-WT dimer exhibits signs of cooperative gating, indicating that despite the abnormal linkage, the correct orientation for opening can occur. We propose that C-terminal interaction functions mainly to tether the protomers together. Comparison of the properties of monomeric and dimeric proton channels speaks against the hypothesis that enhanced gating reflects monomer-dimer interconversion.Key words: voltage-gated proton channels, voltage gating, voltage-sensing domains, phagocytes, coiled-coil, oligomerization, proton currents, pH, dimerization, C-terminus 相似文献
220.
Gürgöze MK Olçücü A Aygün AD Taskin E Kiliç M 《Biological trace element research》2006,111(1-3):23-29
In the present study, the serum and hair levels of zinc, selenium, and copper were determined in children with iron-deficiency
anemia (IDA). A total of 52 anemic children aged 1–4 yr constituted the study group. Fortysix healthy children acted as controls.
The copper and zinc levels were measured with an atomic absorption spectrophometer. Serum and hair selenium was determined
by a spectroflourometric method. The serum zinc and selenium concentrations in the IDA group were found to be significantly
lower and serum copper significantly higher than those in the controls (p<0.05). Lower iron, zinc, and selenium concentrations (p<0.001) but not copper were found in hair (p>0.05). 相似文献