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51.
Background
Despite the high prevalence of smoking among Aboriginal youth, there is a paucity of research related to tobacco use and other risk behaviours among Aboriginal youth living off-reserve in Canada. We used data from the national Youth Smoking Survey to characterize non-traditional tobacco use, exposure to second-hand smoke, and alcohol and drug use among Aboriginal youth living off-reserve. We examined whether these youth were at increased health risk compared with non-Aboriginal youth.Methods
We examined cigarette smoking behaviour, use of other tobacco products, use of alcohol and other drugs, and exposure to second-hand smoke among 2620 Aboriginal youth living off-reserve and 26 223 non-Aboriginal youth in grades 9 to 12 who participated in the 2008/09 Youth Smoking Survey.Results
The prevalence of current smoking among the Aboriginal youth was more than double that among non-Aboriginal youth (24.9% v. 10.4%). Aboriginal youth also had a higher prevalence of regular exposure to second-hand smoke at home (37.3% v. 19.7%) and in cars (51.0% v. 30.3%). Aboriginal youth were more likely than non-Aboriginal youth to be current smokers, to be regularly exposed to second-hand smoke, to have tried marijuana and other illicit drugs, and to engage in binge drinking. They were less likely than non-Aboriginal youth to have tried to quit smoking.Interpretation
Current national estimates of smoking, and alcohol and illicit drug use among youth underestimate the prevalence of these behaviours among Aboriginal youth living off-reserve. Our findings highlight the need for culturally appropriate prevention and cessation policies and programs for this at-risk population.Compared with the general population in Canada, Aboriginal youth start smoking earlier1 and have a higher prevalence of smoking,1–3 with female Aboriginals at greatest risk.1 Research has also shown that Aboriginal youth have high rates of binge drinking1 and are more likely than non-Aboriginal youth to use marijuana.4Despite the high prevalence of smoking among Aboriginal youth in Canada, there is a paucity of research related to their patterns of tobacco use, especially among Aboriginals living off-reserve.5 Most Aboriginals in Canada live off-reserve,6 and those 15 years of age and older are more likely than non-Aboriginals to have chronic health conditions, to drink heavily and to smoke.7 Given that the Canadian Tobacco Control Strategy emphasizes targeting youth, young adults, First Nations, Inuit and other Aboriginal groups,8 a better understanding of tobacco use among Aboriginal youth living off-reserve is required.We conducted this study to examine patterns of tobacco use, exposure to second-hand smoke and the prevalence of alcohol and other drug use among Aboriginal youth living off-reserve. We compared these data with those for non-Aboriginal youth using nationally representative data from the 2008/09 Youth Smoking Survey. 相似文献52.
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54.
Seed dispersal plays a critical role in rainforest regeneration patterns, hence loss of avian seed dispersers in fragmented landscapes may disrupt forest regeneration dynamics. To predict whether or not a plant will be dispersed in fragmented forests, it is necessary to have information about frugivorous bird distribution and dietary composition. However, specific dietary information for frugivorous birds is often limited. In such cases, information on the seed-crushing behaviour, gape width and relative dietary dominance by fruit may be used to describe functional groups of bird species with respect to their potential to disperse similar seeds. We used this information to assess differences in the seed dispersal potential of frugivorous bird assemblages in a fragmented rainforest landscape of southeast Queensland, Australia. The relative abundance of frugivorous birds was surveyed in extensive, remnant and regrowth rainforest sites (16 replicates of each). Large-gaped birds with mixed diets and medium-gaped birds with fruit-dominated diets were usually less abundant in remnants and regrowth than in continuous forest. Small-gaped birds with mixed diets and birds with fruit as a minor dietary component were most abundant in regrowth. We recorded a similar number of seed-crushing birds and large-gaped birds with fruit-dominated diets across site types. Bird species that may have the greatest potential to disperse a large volume and wide variety of plants, including large-seeded plants, tended to be less abundant outside of extensive forests, although one species, the figbird Sphecotheres viridis, was much more abundant in these areas. The results suggest that the dispersal of certain plant taxa would be limited in this fragmented landscape, although the potential for the dispersal of large-seeded plants may remain, despite the loss of several large-gaped disperser species. 相似文献
55.
Forbidden synonymous substitutions in coding regions 总被引:2,自引:0,他引:2
In the evolution of highly conserved genes, a few "synonymous"
substitutions at third bases that would not alter the protein sequence are
forbidden or very rare, presumably as a result of functional requirements
of the gene or the messenger RNA. Another 10% or 20% of codons are
significantly less variable by synonymous substitution than are the
majority of codons. The changes that occur at the majority of third bases
are subject to codon usage restrictions. These usage restrictions control
sequence similarities between very distant genes. For example, 70% of third
bases are identical in calmodulin genes of man and trypanosome. Third-base
similarities of distant genes for conserved proteins are mathematically
predicted, on the basis of the G+C composition of third bases. These
observations indicate the need for reexamination of methods used to
calculate synonymous substitutions.
相似文献
56.
Sperka T Song Z Morita Y Nalapareddy K Guachalla LM Lechel A Begus-Nahrmann Y Burkhalter MD Mach M Schlaudraff F Liss B Ju Z Speicher MR Rudolph KL 《Nature cell biology》2012,14(1):73-79
The tumour suppressor p53 activates Puma-dependent apoptosis and p21-dependent cell-cycle arrest in response to DNA damage. Deletion of p21 improved stem-cell function and organ maintenance in progeroid mice with dysfunctional telomeres, but the function of Puma has not been investigated in this context. Here we show that deletion of Puma improves stem- and progenitor-cell function, organ maintenance and lifespan of telomere-dysfunctional mice. Puma deletion impairs the clearance of stem and progenitor cells that have accumulated DNA damage as a consequence of critically short telomeres. However, further accumulation of DNA damage in these rescued progenitor cells leads to increasing activation of p21. RNA interference experiments show that upregulation of p21 limits proliferation and evolution of chromosomal imbalances of Puma-deficient stem and progenitor cells with dysfunctional telomeres. These results provide experimental evidence that p53-dependent apoptosis and cell-cycle arrest act in cooperating checkpoints limiting tissue maintenance and evolution of chromosomal instability at stem- and progenitor-cell levels in response to telomere dysfunction. Selective inhibition of Puma-dependent apoptosis can result in temporary improvements in maintenance of telomere-dysfunctional organs. 相似文献
57.
58.
59.
Richard M Anthony Anja RJ Schuitema Indra L Bergval Tim J Brown Linda Oskam Paul R Klatser 《Annals of clinical microbiology and antimicrobials》2005,4(1):1-6
Background
Mutations in a small region of the rpoB gene are responsible for most rifamycin resistance in Mycobacterium tuberculosis. In this study we have sequentially generated resistant strains to first rifampicin and then rifabutin. Portions of the rpoB gene were sequenced from 131 randomly selected mutants. Second round selection resulted in a changed frequency of specific mutations.Methods
Mycobacterium tuberculosis (strain Mtb72) rifamycin resistant mutants were selected in vitro with either rifampicin or rifabutin. One mutant R190 (rpoB S522L) selected with rifampicin had a rifampicin MIC of 32 μg/ml but remained sensitive to rifabutin (MIC<0.8 μg/ml). This mutant was subjected to a second round of selection with rifabutin.Results
All 105 first round resistant mutants derived from the parent strain (Mtb72) screened acquired mutations within the 81 bp rpoB hotspot. When the rifampicin resistant but rifabutin sensitive S522L mutant was subjected to a second round of selection, single additional rpoB mutations were identified in 24 (92%) of 26 second round mutants studied, but 14 (54%) of these strains contained mutations outside the 81 bp hotspot (codons 144, 146, 148, 505). Additionally, spontaneous rifabutin resistant mutants were produced at >10 times the frequency by the S522L mutant than the parent strain.Conclusion
First round selection of mutation S522L with rifampicin increased the frequency and changed the spectrum of mutations identified after selection with rifabutin. 相似文献60.
The genome of Rhizobium leguminosarum has recognizable core and accessory components 总被引:3,自引:0,他引:3
Young JP Crossman LC Johnston AW Thomson NR Ghazoui ZF Hull KH Wexler M Curson AR Todd JD Poole PS Mauchline TH East AK Quail MA Churcher C Arrowsmith C Cherevach I Chillingworth T Clarke K Cronin A Davis P Fraser A Hance Z Hauser H Jagels K Moule S Mungall K Norbertczak H Rabbinowitsch E Sanders M Simmonds M Whitehead S Parkhill J 《Genome biology》2006,7(4):R34-20