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排序方式: 共有152条查询结果,搜索用时 31 毫秒
91.
Samar Farha Daniel Laskowski Deepa George Margaret M Park WH Wilson Tang Raed A Dweik Serpil C Erzurum 《Respiratory research》2013,14(1):6
Background
Reduced gas transfer in patients with pulmonary arterial hypertension (PAH) is traditionally attributed to remodeling and progressive loss of pulmonary arterial vasculature that results in decreased capillary blood volume available for gas exchange.Methods
We tested this hypothesis by determination of lung diffusing capacity (DL) and its components, the alveolar capillary membrane diffusing capacity (Dm) and lung capillary blood volume (Vc) in 28 individuals with PAH in comparison to 41 healthy individuals, and in 19 PAH patients over time. Using single breath simultaneous measure of diffusion of carbon monoxide (DLCO) and nitric oxide (DLNO), DL and Dm were respectively determined, and Vc calculated. Dm and Vc were evaluated over time in relation to standard clinical indicators of disease severity, including brain natriuretic peptide (BNP), 6-minute walk distance (6MWD) and right ventricular systolic pressure (RVSP) by echocardiography.Results
Both DLCO and DLNO were reduced in PAH as compared to controls and the lower DL in PAH was due to loss of both Dm and Vc (all p < 0.01). While DLCO of PAH patients did not change over time, DLNO decreased by 24 ml/min/mmHg/year (p = 0.01). Consequently, Dm decreased and Vc tended to increase over time, which led to deterioration of the Dm/Vc ratio, a measure of alveolar-capillary membrane functional efficiency without changes in clinical markers.Conclusions
The findings indicate that lower than normal gas transfer in PAH is due to loss of both Dm and Vc, but that deterioration of Dm/Vc over time is related to worsening membrane diffusion. 相似文献92.
93.
Phosphorylation and degradation of exogenous phosphatidylinositol incorporated into Friend erythroleukemic cells 总被引:2,自引:0,他引:2
C J Hohengasser J T Thornburg P A van Paridon P van der Schaft K W Wirtz 《The Journal of biological chemistry》1986,261(14):6255-6259
Phosphatidyl[2-3H]inositol (PtdIns) obtained from rat skeletal muscle and yeast was introduced into Friend erythroleukemic cells by use of the PtdInstransfer protein or by spontaneous route. The mammalian PtdIns incorporated by the transfer protein appeared metabolically inert while the spontaneously incorporated PtdIns was both phosphorylated to PtdIns-4-phosphate (i.e. 30% of the total PtdIns incorporated) and converted into lyso-PtdIns (i.e. 20% of the total PtdIns incorporated); formation of PtdIns, 4,5-bisphosphate was minimal. The extensive metabolism of the spontaneously incorporated PtdIns strongly suggests that this PtdIns does not rapidly equilibrate with the endogenous PtdIns pools. A similar spontaneous incorporation of yeast PtdIns was accompanied by a negligible degree of phosphorylation and hydrolysis. Evidence is provided that this difference in metabolism reflects the absence of arachidonate in the yeast PtdIns. 相似文献
94.
95.
96.
Barbera A Giraud GD Reller MD Maylie J Morton MJ Thornburg KL 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,279(4):R1157-R1164
The effects of right ventricular (RV) systolic pressure (RVSP) load on fetal myocyte size and maturation were studied. Pulmonary artery (PA) pressure was increased by PA occlusion from mean 47.4 +/- 5.0 (+/-SD) to 71 +/- 13.6 mmHg (P < 0.0001) in eight RVSP-loaded near-term fetal sheep for 10 days. The maximal pressure generated by the RV with acute PA occlusion increased after RVSP load: 78 +/- 7 to 101 +/- 15 mmHg (P < 0.005). RVSP-load hearts were heavier (44.7 +/- 8.4 g) than five nonloaded hearts (31.8 +/- 0.2 g; P < 0.03); heart-to-body weight ratio (10.9 +/- 1.1 and 6.5 +/- 0.9 g/kg, respectively; P < 0.0001). RVSP-RV myocytes were longer (101.3 +/- 10.2 microm) than nonloaded RV myocytes (88.2 +/- 8.1 microm; P < 0. 02) and were more often binucleated (82 +/- 13%) than nonloaded myocytes (63 +/- 7%; P < 0.02). RVSP-loaded myocytes had less myofibrillar volume than did nonloaded hearts (44.1 +/- 4.4% and 56. 1 +/- 2.6%; P < 0.002). We conclude that RV systolic load 1) leads to RV myocyte enlargement, 2) has minor effects on left ventricular myocyte size, and 3) stimulates maturation (increased RV myocyte binucleation). Myocyte volume data suggest that RV systolic loading stimulates both hyperplastic and hypertrophic growth. 相似文献
97.
MCW Chan CY Cheung WH Chui SW Tsao JM Nicholls YO Chan RWY Chan HT Long LLM Poon Y Guan JSM Peiris 《Respiratory research》2005,6(1):135
Background
Fatal human respiratory disease associated with influenza A subtype H5N1 has been documented in Hong Kong, and more recently in Vietnam, Thailand and Cambodia. We previously demonstrated that patients with H5N1 disease had unusually high serum levels of IP-10 (interferon-gamma-inducible protein-10). Furthermore, when compared with human influenza virus subtype H1N1, the H5N1 viruses in 1997 (A/Hong Kong/483/97) (H5N1/97) were more potent inducers of pro-inflammatory cytokines (e.g. tumor necrosis factor-a) and chemokines (e.g. IP-10) from primary human macrophages in vitro, which suggests that cytokines dysregulation may play a role in pathogenesis of H5N1 disease. Since respiratory epithelial cells are the primary target cell for replication of influenza viruses, it is pertinent to investigate the cytokine induction profile of H5N1 viruses in these cells.Methods
We used quantitative RT-PCR and ELISA to compare the profile of cytokine and chemokine gene expression induced by H5N1 viruses A/HK/483/97 (H5N1/97), A/Vietnam/1194/04 and A/Vietnam/3046/04 (both H5N1/04) with that of human H1N1 virus in human primary alveolar and bronchial epithelial cells in vitro.Results
We demonstrated that in comparison to human H1N1 viruses, H5N1/97 and H5N1/04 viruses were more potent inducers of IP-10, interferon beta, RANTES (regulated on activation, normal T cell expressed and secreted) and interleukin 6 (IL-6) in primary human alveolar and bronchial epithelial cells in vitro. Recent H5N1 viruses from Vietnam (H5N1/04) appeared to be even more potent at inducing IP-10 than H5N1/97 virus.Conclusion
The H5N1/97 and H5N1/04 subtype influenza A viruses are more potent inducers of proinflammatory cytokines and chemokines in primary human respiratory epithelial cells than subtype H1N1 virus. We suggest that this hyper-induction of cytokines may be relevant to the pathogenesis of human H5N1 disease. 相似文献98.
The responses to mucosal pressure elevation (physiological pressure: PP) were compared to responses to serosal pressure elevation (non-physiological pressure: NPP) in bullfrog urinary bladders (Rana catesbeiana). The bladders were mounted on vertical chambers as flat sheets. Distension was applied with 98.07 Pa. pressure gradients. PP resulted in increases in transepithelial electrical potential difference (TEP) and short-circuit current (SCC). Electrical resistance (R), urea permeability (P(urea)) and net water flux (J( v)) were not effected. NPP resulted in decreases in TEP (38%), SCC (13%), and R (36%). While P(urea) (97%) and J(v) (96%) increased. PP caused little or no change in the electron microscopic structure of frog bladder while NPP caused irreversible dilation of the lateral intercellular spaces. There were no observable changes in tight junctions under PP or NPP. The subepithelial elements of the bladder became detached from the epithelial layer during NPP suggesting a role for them during PP. 相似文献
99.
Rates and dates of divergence between AIDS virus nucleotide sequences 总被引:28,自引:3,他引:25
100.
An anatomic basis for fetal right ventricular dominance and arterial pressure sensitivity 总被引:2,自引:0,他引:2
Fetal right ventricular dominance of flow and arterial pressure sensitivity were recently recognized but controversial findings. We investigated ventricular volumes, weights and dimensions in order to understand if there were anatomic differences between the ventricles which might explain these differential functional findings in the fetal sheep. Forty-four near term lambs and their hearts were weighed. Right and left ventricular free wall weights were not different. Volumes were measured by generating in vitro pressure-volume relations and by casting the two ventricles after fixation at equal, physiologic pressures. Right ventricular volume was greater than left ventricular volume by both techniques. Ventricular interaction and a restraining effect of the pericardium were present. Measurements of the fixed ventricles and their casts revealed the following: left ventricular wall thickness was slightly greater than right ventricular wall thickness; lateral ventricular diameters were not different but anteroposterior ventricular diameters were much greater in the right than left ventricle. Because of these findings, the right ventricular circumferential radii of curvature were greater than for the left ventricle as was the radius to wall thickness ratio. Greater right ventricular volume and radius to wall thickness ratio may be important factors in right ventricular flow dominance and greater sensitivity to arterial pressure. 相似文献