Quantifying the effects of landscape and habitat characteristics on structuring bird assemblages in urban habitat patches.

Understanding the determinants of biodiversity in fragmented habitats is fundamental for informing sustainable landscape development, especially in urban landscapes that substantially fragment natural habitat. However, the relative roles of landscape and habitat characteristics, as emphasized by two competing frameworks (the island biogeography theory and the habitat diversity hypothesis), in structuring species assemblages in fragmented habitats have not been fully explored. This study investigated bird assemblages at 26 habitat patches (ranging in size from 0.3 to 290.4 ha) in an urban landscape, southwest China, among which habitat type composition and woody plant species composition varied significantly. Through 14 bird surveys conducted over six breeding seasons from 2017 to 2022, we recorded 70 breeding bird species (excluding birds recorded only once and fly-overs, such as raptors, swallows and swifts), with an average of 26 ± 10 (SD) species per patch. We found that patch area had significant direct and indirect effects on bird richness, with the indirect effects mediated by habitat richness (i.e., the number of habitat types). Isolation (measured as the distance to the nearest patch), perimeter to area ratio (PAR), and woody plant richness did not significantly predict variation in bird richness. Furthermore, none of these factors significantly sorted bird species based on their functional traits. However, the overall makeup of bird assemblages was significantly associated with the specific habitat types and woody plant species present in the patches. The results suggest that neither the island biogeography theory nor the habitat diversity hypothesis can fully explain the impacts of habitat fragmentation on bird richness in our study system, with their roles primarily being linked to patch area. The findings that habitat and plant compositions were the major drivers of variation in bird assemblage composition offer valuable insights into urban planning and green initiatives. Conservation efforts should focus not only on preserving large areas, but also on preventing urban monocultures by promoting diverse habitats within those areas, contributing to the persistence of meta-communities.

Avascular osteonecrosis after treatment of SARS: a 3-year longitudinal study.

OBJECTIVE: To investigate the relationship between avascular osteonecrosis (AVN) and corticosteroid treatment given to patients with severe acute respiratory syndrome (SARS). METHODS: Longitudinal study of 71 former SARS patients (mainly health care workers) who had been treated with corticosteroids, with an observation time of 36 months. Magnetic resonance images (MRI) and X-rays of hips, knees, shoulders, ankles and wrists were taken as part of the post-SARS follow-up assessments. RESULTS: Thirty-nine per cent developed AVN of the hips within 3-4 months after starting treatment. Two more cases of hip necrosis were seen after 1 year and another 11 cases of AVN were diagnosed after 3 years, one with hip necrosis and 10 with necrosis in other joints. In total, 58% of the cohort had developed AVN after 3 years of observation. The sole factor explaining AVN in the hip was the total dose of corticosteroids received. CONCLUSION: The use of corticosteroids in SARS has been debated; opinions conflict about whether the immediate benefits in terms of saving lives compensate for the adverse effects, including AVN.

[A case-control study on the mxA polymorphisms and susceptibility to severe acute respiratory syndromes].

OBJECTIVE: To investigate the association between the genetic polymorphisms of myxovirus resistance 1 (MxA) gene and susceptibility to severe acute respiratory syndromes (SARS). METHODS: A case-control study was conducted and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to detect the T/G polymorphism at position-88 in the mxA gene promoter. Information on related factors of SARS was collected using a pre-testing questionnaire. Univariate and multivariate logistic analyses were conducted with SPSS software package. RESULTS: Sixty-six cases and sixty-four controls were selected for the study. Comparing with GG genotype, the proportion of GT genotype were significantly higher in the case group (81.3%) than that in the control group (62.5%)) with an OR (95% CI) of 2.700 (1.208-6.037). Multivariate logistic regression analysis revealed that the significant association remained after factors as wearing masks, protection gowns and eye-protection when contacting with SARS patient etc. were adjusted with an OR (95 % CI) of 2.911 (1.027-8.250). CONCLUSION: mxA promoter-88G/T SNP might be confered to host genetic susceptibility to SARS in Chinese Han population.