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171.
Potential of community-wide chemotherapy or immunotherapy to control the spread of HIV-1 总被引:2,自引:0,他引:2
Whether zidovudine (3'-azido-3'-deoxythymidine, AZT) should be offered to symptomless individuals infected with human immunodeficiency virus type-1 (HIV-1), in the hope of delaying or even preventing progression to AIDS, has been much debated. The discussion has focused on the efficacy of the drug in delaying progression to disease, the severity of its side-effects, and the likelihood of its prolonged and widespread use resulting in zidovudine-resistant strains of the virus. Little attention has been given to the degree to which treatment reduces the infectiousness of symptomless patients, and to the concomitant implications for the overall transmission rate of HIV-1 in the community. Here we use simple mathematical models to show that community treatment with antiviral drugs or immunotherapies that lengthen the incubation period of AIDS without significantly reducing the infectiousness of treated individuals, can increase the rate at which HIV-1 infection spreads (which is fairly obvious) and can even, under certain circumstances, increase the AIDS-related death rate in the community (which is less obvious). 相似文献
172.
The structure of thiostrepton 总被引:2,自引:0,他引:2
173.
Incubation period of AIDS in patients infected via blood transfusion 总被引:14,自引:0,他引:14
Temporal trends in the prevalence of HIV (human immunodeficiency virus) infection are uncertain because of the reluctance of most governments to embark on large-scale programmes of serological surveillance. In the absence of such data, attempts have been made to relate the number of reported cases of AIDS (acquired immune deficiency syndrome) in a defined population to the proportion of that population infected with the virus as a specified time point. One crucial determinant of this relationship is the probability distribution of the incubation period of the disease, with the period defined as the time interval from infection to diagnosis. Recent statistical analysis suggests a mean incubation period of 4.5 years with wide confidence limits, whereas a more heuristic study reports a mean of 15 years. Here we report on a new analysis which reveals age-related differences in the mean (and median) incubation period: 1.97 (1.90) years for children (0-4 yrs old at infection), 8.23 (7.97) years for adults (5-59 yrs old), 5.50 (5.44) years for elderly patients (60 yrs and older). 相似文献
174.
The origin of extant amphibians (Lissamphibia: frogs, salamanders and caecilians) is one of the most controversial questions in vertebrate evolution, owing to large morphological and temporal gaps in the fossil record. Current discussions focus on three competing hypotheses: a monophyletic origin within either Temnospondyli or Lepospondyli, or a polyphyletic origin with frogs and salamanders arising among temnospondyls and caecilians among the lepospondyls. Recent molecular analyses are also controversial, with estimations for the batrachian (frog-salamander) divergence significantly older than the palaeontological evidence supports. Here we report the discovery of an amphibamid temnospondyl from the Early Permian of Texas that bridges the gap between other Palaeozoic amphibians and the earliest known salientians and caudatans from the Mesozoic. The presence of a mosaic of salientian and caudatan characters in this small fossil makes it a key taxon close to the batrachian (frog and salamander) divergence. Phylogenetic analysis suggests that the batrachian divergence occurred in the Middle Permian, rather than the late Carboniferous as recently estimated using molecular clocks, but the divergence with caecilians corresponds to the deep split between temnospondyls and lepospondyls, which is congruent with the molecular estimates. 相似文献
175.
Ramamoorthi N Narasimhan S Pal U Bao F Yang XF Fish D Anguita J Norgard MV Kantor FS Anderson JF Koski RA Fikrig E 《Nature》2005,436(7050):573-577
The Lyme disease agent, Borrelia burgdorferi, is maintained in a tick-mouse cycle. Here we show that B. burgdorferi usurps a tick salivary protein, Salp15 (ref. 3), to facilitate the infection of mice. The level of salp15 expression was selectively enhanced by the presence of B. burgdorferi in Ixodes scapularis, first indicating that spirochaetes might use Salp15 during transmission. Salp15 was then shown to adhere to the spirochaete, both in vitro and in vivo, and specifically interacted with B. burgdorferi outer surface protein C. The binding of Salp15 protected B. burgdorferi from antibody-mediated killing in vitro and provided spirochaetes with a marked advantage when they were inoculated into naive mice or animals previously infected with B. burgdorferi. Moreover, RNA interference-mediated repression of salp15 in I. scapularis drastically reduced the capacity of tick-borne spirochaetes to infect mice. These results show the capacity of a pathogen to use a secreted arthropod protein to help it colonize the mammalian host. 相似文献
176.
M. Anderson 《Cellular and molecular life sciences : CMLS》1978,34(5):587-589
Summary A set of muscle fibres have been found associated with certain tracheoles in the flight muscles of the tsetse fly. It is proposed that those muscles may be involved in sound production in the fly.I am grateful to the Ministry of Overseas Development for a grant in support of this work and to Professor L.H. Finlayson for his advice and criticism. 相似文献
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