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The decision that a particular intervention is not clinically indicated may conceal two quite different ethical assumptions. The first assumption is that the intervention is not of overall benefit to this patient. The second is that limited resources should not be used for this patient. These issues are discussed with reference to cardiac surgery in elderly patients with reference to the main theories of allocation: QALYs, needs theories, the sanctity of life theory, the lottery theory, and market forces.  相似文献   
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The feeding apparatus of the marine nematode Rhabdodemania minima Chitwood, 1936 has been examined with light and transmission electron microscopy. The buccal capsule consists of a posterior region with smooth walls bearing three sets of three minute denticles at its posterior end and three large onchia in its mid region; a middle region with grooved walls; and an anterior region with costae and six odontia. The anterior and middle portions of the buccal capsule are enveloped by the cephalic cuticle, whereas the posterior region, which is set off from the middle region by a buccal seam, is partially enveloped by the anterior end of the esophagus. Two subventral esophageal glands open into the lumen of the esophagus. Secretions of each of three paraesophageal glands are conveyed through a duct in each of the three corresponding corners of the buccal wall to an opening between labia. A pair of wing-like thickenings, termed pterons, embraces the duct of each paraesophageal gland in the posterior and middle regions of the buccal capsule. A model of how the buccal capsule operates is proposed and tested. Morphological and functional aspects of the buccal apparatus and cephalic cuticle are compared with those of other taxa of the Enoplida, and their phylogenetic implications are discussed.  相似文献   
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An exported protein of the erythrocytic stages of the malaria parasite, Plasmodium falciparum, has epitope(s) in common with the surface of the sporozoite stage (1). Two cDNA clones encoding this protein, Ag5.1, have now been isolated and expressed in Escherichia coli. The coding sequence contains a region with strong homology to that of the circumsporozoite protein of P. falciparum. Other features of the sequence can be explained in terms of the observed behaviour of the protein in the parasite life cycle. The Ag5.1 can now be synthesised in bacteria in sufficient amounts to analyse the immune response to this protein.  相似文献   
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In a recent entomopathogenic nematode (EPN) survey in the North West province of South Africa, Oscheius safricana was isolated from soil samples using the Galleria mellonella bait method. Morphological studies using light microscopy and scanning electron microscopy, molecular analysis of the internal transcribed spacer region (ITS), D2\D3 expansion segments of the large subunit rDNA gene (LSU) and concise small subunit rDNA gene (SSU), revealed that it was a new species, described herein as Oscheius safricana n. sp. Oscheius safricana n. sp. was characterised by unique ribosomal DNA sequences, amphidelphic reproduction, six separate lips each two bristle-like sensillae, narrow pharynx, valvated basal bulb, lateral field with four lines, leptoderan and closed bursa and fused spicules. This EPN belongs to the group Insectivorus and is morphologically closest to O. necromenus, O. chongmingensis and O. carolinensis. Oscheius safricana n. sp. is symbiotically associated with Serratia marcescens strain MCB.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:642E1B7E-B88F-4CE0-9D06-4FA9ECA48847  相似文献   
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