Theoretical and practical considerations in the doubly-labelled water (2H2(18)O) method for the measurement of carbon dioxide production rate in man

In the doubly-labelled water (2H2(18)O) method for the measurement of carbon dioxide production rate in man, single exponential disappearance curves for 2H2O and H2(18)O in body water are used; the precision with which the slopes and intercepts of the curves are estimated determines the precision of the estimate of carbon dioxide production rate. In studies with infants, and in computer simulations, the effect of different experimental regimes on the overall precision of the carbon dioxide production estimate was investigated. When the number of data points used was progressively reduced by shortening the total observation period from 7 d (about 3 biological half-lives for the isotopes) to 1 d there was a deleterious effect on precision and in the infants there was an upward bias in the values for carbon dioxide production. When the number of data points was reduced by removing points from the middle of the exponential curves with the maintenance of the 7-d experimental period, precision was also reduced but by less than in the former procedure and there were no consistent trends in the average values for carbon dioxide production.     

Whole body MR imaging in ankylosing spondylitis: a descriptive pilot study in patients with suspected early and active confirmed ankylosing spondylitis

Background  

Ankylosing spondylitis is a chronic inflammatory rheumatic disorder which usually begins in early adulthood. The diagnosis is often delayed by many years. MR imaging has become the preferred imaging method for detection of early inflammation of the axial skeleton in ankylosing spondylitis.     

Residence differences in the health status of elders.

Using data from the 1984 Supplement on Aging to the National Health Interview Survey, this study examined residential differences on a selected group of health status measures among persons 65 years of age and older (N = 11,497). Mean values on indicators of health and impairment for each of the residence categories were examined before and after adjusting for distributional differences in background and demographic characteristics which are associated with both health and residence. Three important conclusions emerged from the analysis: (1) health status does not vary with residence in a unitary fashion; (2) the relationship between residence and health status does not appear to fall along a straightforward rural-urban continuum; and (3) there is both diversity in, and a general patterning of, the significant relationships between health and residence with the extremes of health status located in the rural categories.     

Allergen activates peripheral blood eosinophil nuclear factor-κB to generate granulocyte macrophage-colony stimulating factor, tumour necrosis factor-α and interleukin-8

BACKGROUND: Allergic inflammation is characterized by the influx and activation of eosinophils. Cytokines generated by both resident and infiltrating cells are responsible for the initiation and maintenance of this pathogenesis. This study focuses on allergen-induced activation of eosinophil NF-kappaB and generation of granulocyte macrophage-colony stimulating factor (GM-CSF), TNF-alpha, and IL-8. METHODS: Peripheral blood eosinophils were enriched to >99.9% by Percoll gradient sedimentation and negative magnetic affinity chromatography. NF-kappaB activation by 10 microg/mL house dust mite (HDM) extract was demonstrated immunocytochemically using a monoclonal antibody against the active form of NF-kappaB (NF-kappaBa). The authenticity of NF-kappaB was confirmed by Western blot. Cytokine production was assessed both by immuno-staining of eosinophils and by assay of cytokines in the cell supernatant. RESULTS: Activation of peripheral blood eosinophils from atopic, but not non-atopic, donors induced activation of NF-kappaB, which peaked at 4 h and was accompanied by a decline in IkappaB-alpha. The activation of authentic NF-kappaB was confirmed in gel shift assays. Supershift assays showed p65 to be the major subunit of eosinophil NF-kappaB. Immunofluorescent confocal microscopy demonstrated localization of NF-kappaBa to the nucleus. Following activation, cytokine immunoreactivity was seen in a fraction of the eosinophils and cytokines were released into the supernatant. The NF-kappaB inhibitors, calpain inhibitor 1 (10 microm), pentoxifylline (0.5 mm), pyrrolidine dithiocarbamate (PDTC, 10 microm) or gliotoxin (1 pg/mL) reduced the generation of GM-CSF, TNF-alpha and IL-8 in parallel with their inhibition of NF-kappaB. CONCLUSIONS: HDM allergen activates human eosinophil NF-kappaB leading to the production of the cytokines GM-CSF, TNF-alpha and IL-8. We speculate that a role for eosinophil NF-kappaB-dependent cytokines is to act as an autocrine loop augmenting the survival of eosinophils in vivo.     

慢性低氧时小鼠肺组织低氧诱导因子-1α的表达

目的：研究低氧时小鼠肺组织中低氧诱导因子-1α(HIF-k)表达的变化。方法：实验用雄性小鼠，低氧仓浓度分别为10％、7％、5％。用免疫荧光组织化学技术及共聚焦显微术，检测小鼠在低氧条件下肺组织中HIF-1α表达的变化。结果：正常组小鼠肺组织HIF-1α无表达，低氧组HIF-1α表达增加，且随低氧时间的延长及低氧强度的增加而增强。结论：低氧可诱导小鼠肺组织中HIF-1α的表达增强，(HIF-k)可能参与肺组织细胞凋亡的发生。