首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
OBJECTIVE--To compare the cumulative 21 year incidence of admission to hospital for osteoarthritis of the hip, knee, and ankle in former élite athletes and control subjects. DESIGN--National population based study. SETTING--Finland. SUBJECTS--2049 male athletes who had represented Finland in international events during 1920-65 and 1403 controls who had been classified healthy at the age of 20. MAIN OUTCOME MEASURES--Hospital admissions for osteoarthritis of the hip, knee, and ankle joints identified from the national hospital discharge registry between 1970 and 1990. RESULTS--Athletes doing endurance sports, mixed sports, and power sports all had higher incidences of admission to hospital for osteoarthritis than controls. Age adjusted odds ratios compared with controls were 1.73 (95% confidence interval 0.99 to 3.01, P = 0.063) in endurance, 1.90 (1.24 to 2.92, P = 0.003) in mixed sports athletes, and 2.17 (1.41 to 3.32, P = 0.0003) in power sports athletes. The mean age at first admission to hospital was higher in endurance athletes (70.6) than in other groups (58.2 in mixed sports, 61.9 in power sports, and 61.2 in controls). Among the 2046 respondents to a questionnaire in 1985, the odds ratios for admission to hospital were similar in all three groups after adjusting for age, occupation, and body mass index at 20 (2.37, 2.42, 2.68). CONCLUSIONS--Athletes from all types of competitive sports are at slightly increased risk of requiring hospital care because of osteoarthritis of the hip, knee, or ankle. Mixed sports and power sports lead to increased admissions for premature osteoarthritis, but in endurance athletes the admissions are at an older age.  相似文献   

2.
3.
A rapid, efficient, routine system has been established forAgrobacterium tumefaciens-mediated production of hundreds of fertile transgenic plants from commercially important rice cultivars, including an indica cultivar, Pusa Basmati 1. Calli induced from embryos of mature rice seeds were cocultivated withA. tumefaciens strain LBA4404 carrying the plasmid pTOK233, then exposed to hygromycin selection followed by an efficient regeneration system. Based on the total number of calli co-cultivated, the transformation frequencies of independent transgenic rice plants including cultivars Pusa Basmati 1, E-yi 105, E-wan 5 and Zhong-shu-wan-geng, were 13.5, 13.0, 9.1, and 9.3%, respectively. T1 seeds were harvested within 7–8 mo of initiation of mature embryo cultures. Data from Southern hybridization analysis proved that foreign genes on T-DNA were stably integrated into the rice genome at low copy/site numbers. Mendelian inheritance of the transgenes was confirmed in T1 progeny.  相似文献   

4.
5.
6.
This article examines the work of figures from different cultures who contributed fundamentally to the transition from traditional cultural norms to modern nationalism. These people included Edward Wilmot Blyden of Liberia, Johann Gottfried von Herder of Germany and Wang T'ao of China. They are prime examples of the ‘Creoles’ or ‘historicist intellectuals’ identified in the current literature on the origins of nationalism. Their experiences and their ideas were remarkably similar even though they worked in different times and locations.  相似文献   

7.
  • 1.1. The concentrations of free glycerol, inositol and trehalose in five species of nematodes were determined. Analyses of total inositol content were also made.
  • 2.2. Significant differences in free and bound sugar levels were found between the two good anhydrobiotes Anguina tritici and Ditylenchus dipsaci and the three poor survivors Pangrellus redivivus, D. myceliophagous and Turbatrix aceti.
  • 3.3. Highest trehalose contents were found in desiccated A. tritici and D. dipsaci, but glycerol levels were low.
  • 4.4. P. redivivus and T. aceti contained high concentrations of free glycerol.
  • 5.5. Desiccated A. tritici larvae contained more free and bound inositol than all other species studied, but desiccated D. dipsaci larvae had higher levels of bound inositol than P. redivivus, D. myceliophagous and T. aceti.
  • 6.6. Dramatic reductions in inositol and trehalose contents were found in revived A. tritici larvae and freshly extracted D. dipsaci larvae. This was accompanied by an increase in glycerol content.
  • 7.7. The results are discussed in relation to the possible biochemical adaptations employed by anhydrobiotes during desiccation.
  相似文献   

8.
Bovine tuberculosis (bTB) is a very important disease of cattle in Great Britain, where it has been increasing in incidence and geographical distribution. In addition to cattle, it infects other species of domestic and wild animals, in particular the European badger (Meles meles). Policy to control bTB is vigorously debated and contentious because of its implications for the livestock industry and because some policy options involve culling badgers, the most important wildlife reservoir. This paper describes a project to provide a succinct summary of the natural science evidence base relevant to the control of bTB, couched in terms that are as policy-neutral as possible. Each evidence statement is placed into one of four categories describing the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.  相似文献   

9.
Cut flower producers currently have limited options for nematode control. Four field trials were conducted in 2006 and 2007 to evaluate Midas® (iodomethane:chloropicrin 50:50) for control of root-knot nematodes (Meloidogyne arenaria) on Celosia argentea var. cristata in a commercial floriculture production field in southeastern Florida. Midas (224 kg/ha) was compared to methyl bromide:chloropicrin (98:2, 224 kg/ha), and an untreated control. Treatments were evaluated for effects on Meloidogyne arenaria J2 and free-living nematodes in soil through each season, and roots at the end of each season. Plant growth and root disease were also assessed. Population levels of nematodes isolated from soil were highly variable in all trials early in the season, and generally rebounded by harvest, sometimes to higher levels in fumigant treatments than in the untreated control. Although population levels of nematodes in soil were not significantly reduced during the growing season, nematodes in roots and galling at the end of the season were consistently reduced with both methyl bromide and Midas compared to the untreated control. Symptoms of phytotoxicity were observed in Midas treatments during the first year and were attributed to Fe toxicity. Fertilization was adjusted during the second year to investigate potential fumigant/fertilizer interactions. Interactions occurred at the end of the fourth trial between methyl bromide and fertilizers with respect to root-knot nematode J2 isolated from roots and galling. Fewer J2 were isolated from roots treated with a higher level of Fe (3.05%) in the form of Fe sucrate, and galling was reduced in methyl bromide treated plots treated with this fertilizer compared to Fe EDTA. Reduced galling was also seen with Midas in Fe sucrate fertilized plots compared to Fe EDTA. This research demonstrates the difficulty of reducing high root-knot nematode population levels in soil in subtropical conditions in production fields that have been repeatedly fumigated. Although soil population density may remain stable, root population density and disease can be reduced.  相似文献   

10.
  • 1 Urban areas are predicted to grow significantly in the foreseeable future because of increasing human population growth. Predicting the impact of urban development and expansion on mammal populations is of considerable interest due to possible effects on biodiversity and human‐wildlife conflict.
  • 2 The British government has recently announced a substantial housing programme to meet the demands of its growing population and changing socio‐economic profile. This is likely to result in the construction of high‐density, low‐cost housing with small residential gardens. To assess the potential effects of this programme, we analysed the factors affecting the current pattern of use of residential gardens by a range of mammal species using a questionnaire distributed in wildlife and gardening magazines and via The Mammal Society.
  • 3 Twenty‐two species/species groups were recorded. However, the pattern of garden use by individual species was limited, with only six species/species groups (bats, red fox Vulpes vulpes, grey squirrel Sciurus carolinensis, hedgehog Erinaceus europaeus, mice, voles) recorded as frequent visitors to > 20% of gardens in the survey.
  • 4 There was a high degree of association between the variables recorded in the study, such that it was difficult to quantify the effects of individual variables. However, all species/species groups appeared to be negatively affected by the increased fragmentation and reduced proximity of natural and semi‐natural habitats, decreasing garden size and garden structure, but to differing degrees. Patterns of garden use were most clearly affected by house location (city, town, village, rural), with garden use declining with increasing urbanization for the majority of species/species groups, except red foxes and grey squirrels. Increasing urbanization is likely to be related to a wide range of interrelated factors, any or all of which may affect a range of mammal species.
  • 5 Overall, the probable effects of the planned housing development programme in Britain are not likely to be beneficial to mammal populations, although the pattern of use examined in this study may represent patterns of habitat selection by species rather than differences in distribution or abundance. Consequently, additional data are required on the factors affecting the density of species within urban environments.
  相似文献   

11.
Understanding reproductive processes in parasitic nematodes has the potential to lead to the informed design of new anthelmintics and control strategies. Little is known, however, about the molecular mechanisms underlying sex determination, gametogenesis and reproductive physiology for most parasitic nematodes. Together with comparative analyses of data for the free-living nematode Caenorhabditis elegans, molecular investigations are beginning to provide insights into the processes involved in reproduction and development in parasitic nematodes. Here, we review recent developments, focusing on technological aspects and on molecules associated with sex-specific differences in adult nematodes.  相似文献   

12.
Summary Concentration-response functions for-ionone were established for four German shepherds (Figs. 3 and 4). The dogs were tested in a three choice behavioral apparatus (Fig. 2), and trained, by a restricted operant procedure, to establish an approach-avoidance discrimination between odor and air. Odorant concentrations were presented from an olfactometer calibrated by gas chromatography. Minimum detectable concentrations fell within the range 4.0×104.5–4.0×106.5 molecules/cm3. Concentration-response curves for three of the dogs show a clear double reversal in slope which is statistically significant and which divides the curve into a slowly descending upper limb, best fitted by a parabolic function, and a rapidly descending lower limb, best fitted by a cubic function (Figs. 5 and 6). There is evidence that this division might reflect a dual receptor mechanism. When performance during testing stabilized for a given concentration and the concentration was then lowered by a certain magnitude, the new performance level depended markedly on that magnitude. No evidence was found to suggest that adaptation to the test odor influenced performance. As defined by a differential threshold fraction (Flow/Flow) one dog's ability to discriminate between differences in flow rate fell in the range 0.12–0.08.We thank the U.S. Air Force, Air Force Office of Scientific Research for their generous support of this work (Grant No. 73-2425 to D.G.Moulton).-ionone was donated by Givaudan Inc. (Dr. J. Dorsky). We also thank Mr. Paul Phillips for able technical assistance and Dr. T. Burlingame for gas chromatographic measurements.  相似文献   

13.
Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sister genus Skrjabinodon than Spauligodon major males. Because of the level of uncertainty in the results of ancestral state reconstruction, it is unclear if the existence of male dimorphism in this group represents independent instances of convergent evolution or an ancestral trait lost multiple times. Also, although the number of major males per host was positively correlated with the number of females, the same did not hold true for minor males, whose presence was not associated with any other ecological factor. Nevertheless, the existence of male dimorphism in Spauligodon nematodes is tentatively interpreted as resulting from alternative reproductive tactics, with differences in presence and number of individuals as indicators of differences in fitness, with the lower numbers of minor males per host likely maintained by negative frequency‐dependent selection.  相似文献   

14.
RNA interference (RNAi) is widely used in Caenorhabditis elegans to identify gene function and has been adapted as a high-throughput screening method to identify genes involved in essential processes. The technique has been applied to parasitic nematodes with variable success and we believe that inconsistent outcomes preclude its use as a robust screen with which to identify potential control targets. In this article, key issues that require clarification are discussed, including the mode of delivery of double-stranded RNA to the parasite, the developmental stage targeted and, perhaps of most importance, whether the RNAi pathway (as defined by studies in C. elegans) is fully functional in some parasitic nematodes.  相似文献   

15.
16.
Capsule: Over 50% of saltmarsh breeding Common Redshank have been lost since 1985, with current conservation management having only limited success at halting these declines.

Aims: To update population size and trend estimates for saltmarsh-breeding Redshank in Britain, and to determine whether conservation management implemented since 1996 has been successful in influencing grazing intensity and Redshank population trends.

Methods: A repeat national survey of British saltmarsh was conducted in 2011 at sites previously visited in 1985 and 1996. Redshank breeding density and grazing pressure were recorded at all sites; the presence of conservation management was additionally recorded for English sites. Results from all three national surveys were used to update population size and trend estimates, and to investigate changes in grazing pressure and breeding density on sites with and without conservation management.

Results: Of the 21 431 pairs breeding on saltmarsh in 1985, 11 946 pairs remained in 2011, with the highest proportion of this population found in East Anglia. From 1985, British breeding densities declined at a rate of 1 pair km?2 year?1, representing a loss of 52.8% of breeding pairs over 26 years, although regional trends varied across different time periods. Grazing pressures did not change markedly with conservation management. Redshank declines were less severe on conservation-managed sites in East Anglia and the South of England where grazing pressures remained low, though were more severe on conservation-managed sites in the North West where heavy grazing persisted.

Conclusion: Saltmarsh-breeding Redshank declines continue and are likely to be driven by a lack of suitable nesting habitat. Conservation management schemes and site protection implemented since 1996 appear not to be delivering the grazing pressures and associated habitat conditions required by this species, particularly in the North West of England, though habitat changes may not be linked to unsuitable grazing management in all regions. An in-depth understanding of grazing practices, how conservation management guidelines could be improved, and the likely success of more long-term management solutions is needed urgently.  相似文献   

17.
18.
Otfinowski  Rafael  Coffey  Victory 《Plant and Soil》2020,453(1-2):459-471
Plant and Soil - We examined how restoration affects the structure and function of grasslands belowground by relating changes in the morphology and architecture of root systems of dominant plants...  相似文献   

19.
20.
In order to confirm or refute the relay role of lagomorphs in the evolution of the Trichostrongylina (Nematoda), the following points were studied by summarizing previous works on the subject: the chronology of the life cycles (27 conducted in natural hosts, lagomorphs, ruminants or arvicolin rodents; 14 in experimental hosts); the parasitic phase in the experimental host and the adaptation involved; the migration of the parasites into the tissues of the host; the morphogenesis of larval stages and molecular phylogeny. These data confirm, in their entirety, that lagomorphs may be considered as "relay" hosts in the evolution of the Trichostrongylina.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号