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Insight into how humans interact helps further understanding of the transmission of infectious diseases. For diseases such as pertussis, infants are at particular risk for severe outcomes. To understand the contact pattern of infants, especially those too young to be vaccinated, we sent contact diaries to a representative sample of 1000 mothers in the United Kingdom. We received 115 responses with a total of 758 recorded contacts. The average number of daily contacts for an infant was 6.68 overall and 5.7 for those aged ≤10 weeks. Of the latter, 2.1 (37%) contacts were with non-household members and were >15 minutes duration, suggesting that a cocooning programme may miss a substantial proportion of exposures leading to disease transmission. The least contact was between adolescents and infants. Thus the impact of adolescent (pertussis) vaccination on infants would likely be limited, unless it reduces transmission to other age groups whose contact with infants is greater.  相似文献   
44.
On Caribbean reefs, colonies of the hydrocoral Millepora alcicornis are capable of pursuing and overgrowing arborescent octocorals (Wahle 1980 ). Nearly four decades since these interactions were described, we quantified arborescent octocorals encrusted by Millepora spp. (Linnaeus 1758) on shallow reefs in St. John, U.S. Virgin Islands, and evaluated encrusted colonies for evidence of an origin through pursuit. In 2014, 8% of octocorals (n=1684 colonies) were encrusted by Millepora spp., and in 2015, 12% were encrusted (n=847 colonies). Millepora spp. encrusted colonies of 10 octocoral genera, and in 2014, the most frequently encrusted were Eunicea spp. (40% of encrusted octocorals); in 2015, the most frequently encrusted were Gorgonia spp. (46% of encrusted colonies). In both years, ≥67% of encrusted octocorals were >21 cm from other colonies of Millepora spp.; 7% of octocorals were >1.3 m from colonies of Millepora spp. in 2014; and 16% of octocorals were >2.0 m from colonies of Millepora spp. in 2015. Relative to the ~5% of octocorals encrusted by Millepora spp. in Jamaica in the late 1970s, a high percentage (~9%) of octocorals were encrusted by Millepora spp. in St. John in 2014 and 2015. The large distances from most encrusted octocorals to the nearest colonies of Millepora spp. in St. John are inconsistent with a hypothesized origin through pursuit, contact, and overgrowth (sensu Wahle 1980 ).  相似文献   
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Synchronous cell division in Euglena gracilis (strain Z) was obtained in 24-hour light cycles consisting of 10 hours of light and 14 hours of darkness; cell division was restricted to the dark period. Photosynthetic capacity was found to vary in a cyclic manner during the cell cycle, reaching a peak 2 hours before the onset of darkness. Light reactions were investigated during the cell cycle to determine what role they played in the control of the observed rhythmic changes in capacity. Light-saturation curves showed no major change in the light-limited region. No fluctuations were found in Hill reaction activity or photoreduction of methyl red during the cell cycle. These results imply that the reactions comprising photosystems I and II do not generate the capacity rhythm.  相似文献   
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A review, outlining the origins and subsequent development of the triketone class of herbicidal 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors.  相似文献   
47.
Utilizing X-ray crystallography and molecular modeling, highly potent and selective peptidomimetic thrombin inhibitors have been designed containing a rigid piperazinedione template. The synthesis and biological activity of these compounds will be described.  相似文献   
48.
Potent and selective thrombin inhibitors have been prepared with a piperazinedione template and L-amino acids. Likewise, incorporation of D-amino acids led to potent inhibitors with a novel mode of binding. Herein, the structure activity relationships and structural aspects of these compounds will be described.  相似文献   
49.
Metabolic scaling is the relationship between organismal metabolic rate and body mass. Understanding the patterns and causes of metabolic scaling provides a powerful foundation for predicting biological processes at the level of individuals, populations, communities, and ecosystems. Despite intense interest in, and debate on, the mechanistic basis of metabolic scaling, relatively little attention has been paid to metabolic scaling in clonal animals with modular construction, such as colonial cnidarians, bryozoans, and colonial ascidians. Unlike unitary animals, modular animals are structural individuals subdivided into repeated morphological units, or modules, each able to acquire, process, and share resources. A modular design allows flexibility in organism size and shape with consequences for metabolic scaling. Furthermore, with careful consideration of the biology of modular animals, the size and shape of individual colonies can be experimentally manipulated to test competing theories pertaining to metabolic scaling. Here, we review metabolic scaling in modular animals and find that a wide range of scaling exponents, rather than a single value, has been reported for a variety of modular animals. We identify factors influencing variation in intraspecific scaling in this group that relate to the general observation that not all modules within a colony are identical. We highlight current gaps in our understanding of metabolic scaling in modular animals, and suggest future research directions, such as manipulating metabolic states and comparisons among species that differ in extent of module integration.  相似文献   
50.
Inflammatory bowel disease (IBD) is a chronic, inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. This study examined the effects of aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (Actinidia deliciosa) using in vitro models of IBD. These models comprised primary macrophages and intestinal epithelial cells isolated from C57BL/5J and interleukin-10 gene deficient (Il10−/−) mice and RAW 264.7, a murine macrophage-like cell line. All four kiwifruit extracts reduced the activation of these models after lipopolysaccharide stimulation, decreasing nitric oxide and cytokine secretion by both Il10−/− and wild-type cells. The ethyl acetate extracts exhibited the highest anti-inflammatory activity, with almost complete suppression of lipopolysaccharide-stimulated macrophage activation. These results suggest that kiwifruit extracts have significant anti-inflammatory activity relevant to IBD. We suggest that the Il10−/− mouse is a suitable model for further study of these compounds.  相似文献   
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