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Few quantitative measures of genome architecture or organization exist to support assumptions of differences between microorganisms that are broadly defined as being free-living or pathogenic. General principles about complete proteomes exist for codon usage, amino acid biases and essential or core genes. Genome-wide shifts in amino acid usage between free-living and pathogenic microorganisms result in fundamental differences in the complexity of their respective proteomes that are size and gene content independent. These differences are evident across broad phylogenetic groups–a result of environmental factors and population genetic forces rather than phylogenetic distance. A novel comparative analysis of amino acid usage–utilizing linguistic analyses of word frequency in language and text–identified a global pattern of higher peptide word repetition in 376 free-living versus 421 pathogen genomes across broad ranges of genome size, G+C content and phylogenetic ancestry. This imprint of repetitive word usage indicates free-living microorganisms have a bias for repetitive sequence usage compared to pathogens. These findings quantify fundamental differences in microbial genomes relative to life-history function.  相似文献   

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Reduction of neonatal mortality and the rate of stillbirth may be expected from improved management of spontaneous labor and delivery.Neither roentgenographic measurement nor the inception of fetal movement or heartbeat nor any other single test is an index of fetal maturity; all must be considered together. Prenatal care, particularly supplemented diet, will help to avoid premature delivery, or at least to prolong pregnancy; since the fetus undergoes accelerated growth during the last weeks of pregnancy, even slight extension of gestation increases the chances for survival. Analgesia in the first stage of premature labor is contraindicated. Only low spinal anesthesia and other types of conduction anesthesia should be employed for later stages. The fetal membranes should be preserved as long as possible, but premature rupture does not call for immediate termination of pregnancy. Deep episiotomy and prophylactic outlet forceps are routinely employed to hasten the second stage of premature delivery and to protect the immature fetus. Breech presentation is managed by unassisted expulsion or by forceps extraction of the head. The umbilical cord is not immediately severed on delivery; administration of oxytocic drugs after the second stage of labor, combined with gentle stripping of the cord, results in rapid transfer of increased amount of placental blood. The airways of the infant should be immediately cleared. Artificial respiration may be necessary and it must be gentle.All premature infants should receive supplementary oxygen to render breathing regular and more efficient. They should be insulated immediately in controlled temperature and humidity, and they should be handled little.  相似文献   

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Microbes are known for their unique ability to adapt to varying lifestyle and environment, even to the extreme or adverse ones. The genomic architecture of a microbe may bear the signatures not only of its phylogenetic position, but also of the kind of lifestyle to which it is adapted. The present review aims to provide an account of the specific genome signatures observed in microbes acclimatized to distinct lifestyles or ecological niches. Niche-specific signatures identified at different levels of microbial genome organization like base composition, GC-skew, purine-pyrimidine ratio, dinucleotide abundance, codon bias, oligonucleotide composition etc. have been discussed. Among the specific cases highlighted in the review are the phenomena of genome shrinkage in obligatory host-restricted microbes, genome expansion in strictly intra-amoebal pathogens, strand-specific codon usage in intracellular species, acquisition of genome islands in pathogenic or symbiotic organisms, discriminatory genomic traits of marine microbes with distinct trophic strategies, and conspicuous sequence features of certain extremophiles like those adapted to high temperature or high salinity.  相似文献   

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《Reproductive biology》2014,14(3):190-199
Different environmental and lifestyle factors may interfere with the normal disjunction of sister chromatids/chromosomes during meiosis and may cause aneuploidy. The aim of the study was to examine the association between lifestyle factors and sperm aneuploidy. The study population consisted of 212 healthy men under 45 years of age attending an infertility clinic for diagnostic purposes and who had a normal semen concentration of 20–300 × 106 mL or slight oligozoospermia (semen concentration of 15–20 × 106/mL). All participants were interviewed and provided a semen sample. Sperm aneuploidy was assessed using multicolor FISH (DNA probes specific for chromosomes X, Y, 18, 13, 21). Results from the study suggest that lifestyle factors are related to sperm aneuploidy. A positive relationship was found between coffee drinking everyday and the lack of chromosome X or Y, as well as coffee drinking 1–6 times per week and additional chromosome 18. Wearing boxer shorts decrease the copy number changes in the whole chromosome 18, the number of additional chromosome 18 and the lack of chromosome 13. Additionally, obesity (BMI 30–40 kg/m2) was positively associated with additional chromosome 21 after being adjusted for potential confounders. These findings demonstrate that changing the men's lifestyle habits may contribute to reduction of the incidence of sperm aneuploidy. It is necessary that men continue to follow sensible health advice concerning excess weight, coffee drinking and wearing tight fitting underwear. As this is the first such study to examine different lifestyle factors and sperm aneuploidy, the results need to be confirmed on larger population.  相似文献   

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Medicare conducted a payment demonstration to evaluate the effectiveness of two intensive lifestyle modification programs in patients with symptomatic coronary artery disease: the Dr. Dean Ornish Program for Reversing Heart Disease (Ornish) and Cardiac Wellness Program of the Benson-Henry Mind Body Institute. This report describes the changes in cardiac risk factors achieved by each program during the active intervention year and subsequent year of follow-up. The demonstration enrolled 580 participants who had had an acute myocardial infarction, had undergone coronary artery bypass graft surgery or percutaneous coronary intervention within 12 months, or had documented stable angina pectoris. Of these, 98% completed the intense 3-month intervention, 71% the 12-month intervention, and 56% an additional follow-up year. Most cardiac risk factors improved significantly during the intense intervention period in both programs. Favorable changes in cardiac risk factors and functional cardiac capacity were maintained or improved further at 12 and 24 months in participants with active follow-up. Multivariable regressions found that risk-factor improvements were positively associated with abnormal baseline values, Ornish program participation for body mass index and systolic blood pressure, and with coronary artery bypass graft surgery. Expressed levels of motivation to lose weight and maintain weight loss were significant independent predictors of sustained weight loss (p = 0.006). Both lifestyle modification programs achieved well-sustained reductions in cardiac risk factors.  相似文献   

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Locating sounds in realistic scenes is challenging because of distracting echoes and coarse spatial acoustic estimates. Fortunately, listeners can improve performance through several compensatory mechanisms. For instance, their brains perceptually suppress short latency (1-10 ms) echoes by constructing a representation of the acoustic environment in a process called the precedence effect. This remarkable ability depends on the spatial and spectral relationship between the first or precedent sound wave and subsequent echoes. In addition to using acoustics alone, the brain also improves sound localization by incorporating spatially precise visual information. Specifically, vision refines auditory spatial receptive fields and can capture auditory perception such that sound is localized toward a coincident visual stimulus. Although visual cues and the precedence effect are each known to improve performance independently, it is not clear whether these mechanisms can cooperate or interfere with each other. Here we demonstrate that echo suppression is enhanced when visual information spatially and temporally coincides with the precedent wave. Conversely, echo suppression is inhibited when vision coincides with the echo. These data show that echo suppression is a fundamentally multisensory process in everyday environments, where vision modulates even this largely automatic auditory mechanism to organize a coherent spatial experience.  相似文献   

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