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本文报道海拔3417m和4280m地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示:3417m和4280m世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度(Sao2)随运动负荷的增加而降低。海拔3417m藏、汉族的△Sao2分别为7.46%和10.03%,4280m处为8.57%和13.75%,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。 相似文献
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Christopher J. Bayne Patricia M. Buckley Peggy C. DeWan 《Experimental parasitology》1980,50(3):409-416
Sporocysts of Schistosoma mansoni (PR1 strain) survive and grow in Biomphalaria glabrata PR albino strain snails, whereas they are encapsulated and die in B. glabrata 10R2 strain snails. These processes also occur in an in vitro system in which the only living cells are those of sporocysts and snail hemolymph. Hemocytes of the susceptible snail are normally not effective in damaging sporocysts. However, when the encounter occurred in the presence of cell-free plasma from resistant snails, previously impotent hemocytes severely damaged sporocysts in 24 hr. The cytotoxic capacity of resistant strain hemocytes was not altered by plasma from susceptible snails. Furthermore, it was retained even when plasma was replaced by culture medium free of snail components. The nature of the plasma factor(s) which facilitated damage by otherwise impotent hemocytes is discussed, and evidence is evaluated for the hypothesis that snail resistance is dependent upon the specificity of cytophilic factors present both in the plasma and on the hemocyte plasma membranes. 相似文献
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DON AT AGOSTI 《Systematic Entomology》1994,19(2):93-117
Abstract. The holarctic ant tribe Formicini is revised, the new genus Bajcaridris described, and possible phylogenetic relationships are discussed. The subgenus Iberoformica is synonymized with Formica. A synopsis, diagnosis and keys to the genera are provided. 相似文献
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Background
Many musculoskeltal injuries in the workplace have been attributed to the repetitive loading of muscle and soft tissues. It is not disputed that muscular fatigue is a risk factor for musculoskeltal injury, however the disparity between gender with respect to muscular fatigability and rate of recovery is not well understood. Current health and safety guidelines do not account for sex differences in fatiguability and may be predisposing one gender to greater risk. The purpose of this study was to quantify the sex differences in fatigue development and recovery rate of lower and upper body musculature after repeated bouts of sustained isometric contractions.Methods
Twenty-seven healthy males (n = 12) and females (n = 15) underwent bilateral localized fatigue of either the knee extensors (male: n = 8; female: n = 8), elbow flexors (male: n = 8; female: n = 10), or both muscle groups. The fatigue protocol consisted of ten 30-second sub-maximal isometric contractions. The changes in maximum voluntary contraction (MVC), electrically evoked twitches, and motor unit activation (MUA) were assessed along with the ability to control the sustained contractions (SLP) during the fatigue protocol using a mixed four-factor repeated measures ANOVA (gender × side × muscle × time) design with significance set at p < 0.05.Results
There was a significant loss of MVC, MUA, and evoked twitch amplitude from pre- to post-fatigue in both the arms and legs. Males had greater relative loss of isometric force, a higher rate of fatigue development, and were less capable of maintaining the fatiguing contractions in the legs when compared to the females.Conclusion
The nature of the induced fatigue was a combination of central and peripheral fatigue that did not fully recover over a 45-minute period. The results appear to reflect sex differences that are peripheral, and partially support the muscle mass hypothesis for explaining differences in muscular fatigue.7.
John Paul SanGiovanni Dan E. Arking Sudha K. Iyengar Michael Elashoff Traci E. Clemons George F. Reed Alice K. Henning Theru A. Sivakumaran Xuming Xu Andrew DeWan Elvira Agrón Elena Rochtchina Carolyn M. Sue Jie Jin Wang Paul Mitchell Josephine Hoh Peter J. Francis Michael L. Klein Emily Y. Chew Aravinda Chakravarti 《PloS one》2009,4(5)
Background
Age-related macular degeneration (AMD), a chronic neurodegenerative and neovascular retinal disease, is the leading cause of blindness in elderly people of western European origin. While structural and functional alterations in mitochondria (mt) and their metabolites have been implicated in the pathogenesis of chronic neurodegenerative and vascular diseases, the relationship of inherited variants in the mitochondrial genome and mt haplogroup subtypes with advanced AMD has not been reported in large prospective cohorts.Methodology/Prinicipal Findings
We examined the relationship of inherited mtDNA variants with advanced AMD in 1168 people using a three-stage design on samples from 12-year and 10-year prospective studies on the natural history of age-related eye disease. In Stage I we resequenced the entire genome in 99 elderly AMD-free controls and 215 people with advanced AMD from the 12-year study. A consistent association with AMD in 14 of 17 SNPs characterizing the mtDNA T haplogroup emerged. Further analysis revealed these associations were driven entirely by the T2 haplogroup, and characterized by two variants in Complex I genes (A11812G of MT-ND4 and A14233G of MT-ND6). We genotyped T haplogroups in an independent sample of 490 cases and 61 controls from the same study (Stage II) and in 56 cases and 246 controls from the 10-year study (Stage III). People in the T2 haplogroup were approximately 2.5 times more likely to have advanced AMD than their peers (odds ratio [OR] = 2.54, 95%CI 1.36–4.80, P≤0.004) after considering the totality of evidence. Findings persisted after considering the impact of AMD-associated variants A69S and Y402H (OR = 5.19, 95%CI 1.19–22.69, P≤0.029).Conclusion
Loci defining the mtDNA T2 haplogroup and Complex I are reasonable targets for novel functional analyses and therapeutic research in AMD. 相似文献8.
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Relationships in the Drosophila obscura species group, inferred from mitochondrial cytochrome oxidase II sequences 总被引:2,自引:0,他引:2
We compare the sequences for the mitochondrial cytochrome oxidase II gene
of 13 species of the Drosophila obscura group. The survey includes six
members of the D. affinis subgroup, four of the D. pseudoobscura subgroup,
and three of the D. obscura subgroup. In all species, the gene is 688
nucleotides in length, encoding a protein of 229 amino acids plus the first
position T of the stop codon. The sequences show the typical
high-transition bias for closely related species, but that bias is
essentially eliminated for species pairs of > 5% sequence divergence.
The phylogenetic relationships in the species group are inferred using both
neighbor-joining and maximum parsimony. The two procedures give comparable
results, showing that the D. affinis and D. pseudoobscura subgroups are
monophyletic groupings that appear to have closer affinities to one another
than either has to the D. obscura subgroup. We use transversion distances
to estimate times of divergence, on the basis of three different estimates
of the time of separation of the D. obscura species group from the D.
melanogaster group. If that event occurred 35 Mya, then we can estimate the
origin of the nearctic forms at approximately 22 Mya and the separation of
the D. affinis and D. pseudoobscura subgroups at approximately 17 Mya.
相似文献
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土典霉金色变种AT8951菊粉酶粗酶液经硫酸铵分段沉淀、DEAE Cellulose DE32离子交换、超滤、Sephadex G-150凝胶过滤和FPLC,获得两个菊粉酶组分EⅠ和EⅡ,经分析型FPLG和PAGE鉴定为单一纯和分析纯。EⅠ分子量为66KD,最适作用温度和pH分别55℃和5.8;EⅡ分子量为56KD,最适作用温度为57℃,最适pH为6.0。EⅠ和EⅡ皆为糖蛋白,多糖含量分别为24.7%和22%,都属于内切酶。本文还对EⅠ和EⅡ的Km值和I/s值,温度、pH、离子对酶活作用的影响等进行了研究。 相似文献