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61.
EG Ciolac SS Mantuani CM Neiva CEL Verardi DM Pess?a-Filho L Pimenta 《Biology of sport / Institute of Sport》2015,32(2):103-108
The aim of the present study was to analyse the usefulness of the 6-20 rating of perceived exertion (RPE) scale for prescribing and self-regulating high-intensity interval training (HIT) in young individuals. Eight healthy young subjects (age = 27.5±6.7 years) performed maximal graded exercise testing to determine their maximal and reserve heart rate (HR). Subjects then performed two HIT sessions (20 min on a treadmill) prescribed and regulated by their HR (HR: 1 min at 50% alternated with 1 min at 85% of reserve HR) or RPE (RPE: 1 minute at the 9-11 level [very light-fairly light] alternated with 1 minute at the 15-17 level [hard-very hard]) in random order. HR response and walking/running speed during the 20 min of exercise were compared between sessions. No significant difference between sessions was observed in HR during low- (HR: 135±15 bpm; RPE: 138±20 bpm) and high-intensity intervals (HR: 168±15 bpm; RPE: 170±18 bpm). Walking/running speed during low- (HR: 5.7±1.2 km · h−1; RPE: 5.7±1.3 km · h−1) and high-intensity intervals (HR: 7.8±1.9 km · h−1; RPE: 8.2±1.7 km · h−1) was also not different between sessions. No significant differences were observed in HR response and walking/running speed between HIT sessions prescribed and regulated by HR or RPE. This finding suggests that the 6-20 RPE scale may be a useful tool for prescribing and self-regulating HIT in young subjects. 相似文献
62.
63.
Sullivan T. Y.; DeWeese E. L.; Yu P. L.; Aronoff G. R. 《Journal of applied physiology》1987,63(6):2542-2548
Airway anesthesia with aerosolized lidocaine has been associated with an increase in minute ventilation (VE) during CO2 inhalation. The increase in VE may be due to increased neuromuscular output or decreased mechanical load on breathing. To evaluate this we measured VE, breathing pattern, mouth occlusion pressure, and lung mechanics in 20 normal subjects during room-air breathing and then inhalation of 6% CO2-94% O2, before and after airway anesthesia. Measurements of lung mechanics included whole-lung resistance, dynamic and static compliance, and functional residual capacity. Airway anesthesia had no detectable effect on any measurements during room-air breathing. During CO2 inhalation, airway anesthesia produced increases in VE and mean inspiratory flow rate (VT/TI) and more negative inspiratory pleural pressure but had no detectable effect on lung mechanics or mouth occlusion pressure. Pleural pressure was more negative during the latter 25% of inspiration. We concluded that airway receptors accessible to airway anesthesia play a role in determining neuromuscular output during CO2 inhalation. 相似文献
64.
Loss of meiosis in Aspergillus 总被引:2,自引:0,他引:2
If strictly mitotic asexual fungi lack recombination, the conventional view
predicts that they are recent derivatives from older meiotic lineages. We
tested this by inferring phylogenetic relationships among closely related
meiotic and strictly mitotic taxa with Aspergillus conidial (mitotic)
states. Phylogenies were constructed by using DNA sequences from the
mitochondrial small ribosomal subunit, the nuclear ribosomal internal
transcribed spacers, and the nuclear 5.8S ribosomal gene. Over 920 bp of
sequence was analyzed for each taxon. Phylogenetic analysis of both the
mitochondrial and nuclear data sets showed at least four clades that
possess both meiotic and strictly mitotic taxa. These results support the
hypothesis that strictly mitotic lineages arise frequently from more
ancient meiotic lineages with Aspergillus conidial states. Many of the
strictly mitotic species examined retained characters that may be vestiges
of a meiotic state, including the production of sclerotia, sclerotium-like
structures, and hulle cells.
相似文献
65.
Partial 18S rRNA sequences of five chelicerate arthropods plus a
crustacean, myriapod, insect, chordate, echinoderm, annelid, and
platyhelminth were compared. The sequence data were used to infer phylogeny
by using a maximum-parsimony method, an evolutionary-distance method, and
the evolutionary-parsimony method. The phylogenetic inferences generated by
maximum-parsimony and distance methods support both monophyly of the
Arthropoda and monophyly of the Chelicerata within the Arthropoda. These
results are congruent with phylogenies based on rigorous cladistic analyses
of morphological characters. Results support the inclusion of the
Arthropoda within a spiralian or protostome coelomate clade that is the
sister group of a deuterostome clade, refuting the hypothesis that the
arthropods represent the "primitive" sister group of a protostome coelomate
clade. Bootstrap analyses and consideration of all trees within 1% of the
length of the most parsimonious tree suggest that relationships between the
nonchelicerate arthropods and relationships within the chelicerate clade
cannot be reliably inferred with the partial 18S rRNA sequence data. With
the evolutionary-parsimony method, support for monophyly of the Arthropoda
is found in the majority of the combinations analyzed if the coelomates are
used as "outgroups." Monophyly of the Chelicerata is supported in most
combinations assessed. Our analyses also indicate that the
evolutionary-parsimony method, like distance and parsimony, may be biased
by taxa with long branches. We suggest that a previous study's inference of
the Arthropoda as paraphyletic may be the result of (a) having two few
arthropod taxa available for analysis and (b) including long-branched taxa.
相似文献
66.
67.
Pathological and molecular mechanisms of prostate carcinogenesis: implications for diagnosis, detection, prevention, and treatment 总被引:10,自引:0,他引:10
De Marzo AM DeWeese TL Platz EA Meeker AK Nakayama M Epstein JI Isaacs WB Nelson WG 《Journal of cellular biochemistry》2004,91(3):459-477
Prostate cancer is an increasing threat throughout the world. As a result of a demographic shift in population, the number of men at risk for developing prostate cancer is growing rapidly. For 2002, an estimated 189,000 prostate cancer cases were diagnosed in the U.S., accompanied by an estimated 30,200 prostate cancer deaths [Jemal et al., 2002]. Most prostate cancer is now diagnosed in men who were biopsied as a result of an elevated serum PSA (>4 ng/ml) level detected following routine screening. Autopsy studies [Breslow et al., 1977; Yatani et al., 1982; Sakr et al., 1993], and the recent results of the Prostate Cancer Prevention Trial (PCPT) [Thompson et al., 2003], a large scale clinical trial where all men entered the trial without an elevated PSA (<3 ng/ml) were subsequently biopsied, indicate the prevalence of histologic prostate cancer is much higher than anticipated by PSA screening. Environmental factors, such as diet and lifestyle, have long been recognized contributors to the development of prostate cancer. Recent studies of the molecular alterations in prostate cancer cells have begun to provide clues as to how prostate cancer may arise and progress. For example, while inflammation in the prostate has been suggested previously as a contributor to prostate cancer development [Gardner and Bennett, 1992; Platz, 1998; De Marzo et al., 1999; Nelson et al., 2003], research regarding the genetic and pathological aspects of prostate inflammation has only recently begun to receive attention. Here, we review the subject of inflammation and prostate cancer as part of a "chronic epithelial injury" hypothesis of prostate carcinogenesis, and the somatic genome and phenotypic changes characteristic of prostate cancer cells. We also present the implications of these changes for prostate cancer diagnosis, detection, prevention, and treatment. 相似文献
68.
The sparse coding hypothesis has enjoyed much success in predicting response properties of simple cells in primary visual cortex (V1) based solely on the statistics of natural scenes. In typical sparse coding models, model neuron activities and receptive fields are optimized to accurately represent input stimuli using the least amount of neural activity. As these networks develop to represent a given class of stimulus, the receptive fields are refined so that they capture the most important stimulus features. Intuitively, this is expected to result in sparser network activity over time. Recent experiments, however, show that stimulus-evoked activity in ferret V1 becomes less sparse during development, presenting an apparent challenge to the sparse coding hypothesis. Here we demonstrate that some sparse coding models, such as those employing homeostatic mechanisms on neural firing rates, can exhibit decreasing sparseness during learning, while still achieving good agreement with mature V1 receptive field shapes and a reasonably sparse mature network state. We conclude that observed developmental trends do not rule out sparseness as a principle of neural coding per se: a mature network can perform sparse coding even if sparseness decreases somewhat during development. To make comparisons between model and physiological receptive fields, we introduce a new nonparametric method for comparing receptive field shapes using image registration techniques. 相似文献
69.
静磁场对单株人体体表正常菌生长影响的研究 总被引:1,自引:0,他引:1
本文通过40mT和120mT两种静磁场作用下表皮葡萄球菌生长过程的研究,发现试验所选强度静磁场加速了表皮葡萄球菌在对数生长期的生长速率,而在进入稳定生长期后其生长速率反而低于对照组,但就整个生长周期而言,静磁场作用下表皮葡萄球菌的总量大于对照组,表明了试验所选静磁场对表皮葡萄球菌生长有一定促进作用. 相似文献
70.