Influence of lung aeration on diaphragmatic contractility during a spontaneous breathing trial: an ultrasound study.

BACKGROUND: A spontaneous breathing trial (SBT) is a major diagnostic tool to predict successfully extubation in patients. Several factors may lead to weaning failure, including the degree of lung aeration loss and diaphragm dysfunction. The main objective was to compare the diaphragmatic contractility between patients with high lung aeration loss and low lung aeration loss during a 30-minute SBT by ultrasound. METHODS: This was a prospective single-center study. Lung ultrasound aeration score (LUS) and diaphragmatic thickening fraction (DTF) were measured during mechanical ventilation 1 h before SBT (T-1), 30 min (T1), and 120 min (T2) after the start of the SBT during quiet breathing. The right and left DTF were compared between patients with LUS ≥ 14 (high lung aeration loss), considered at high risk of post-extubation distress, and those with LUS < 14 (low lung aeration loss). The relationship between the LUS and DTF and the changes in LUS and DTF from T-1 to T2 in patients with LUS ≥ 14 were assessed. RESULTS: Forty-nine patients were analyzed; 33 had LUS ≥ 14 and 16 had LUS < 14 at T1. The DTF at T1 was significantly higher in patients with LUS ≥ 14 than in those with LUS < 14: the right median (IQR) DTF was 22.2% (17.1 to 30.9%) vs. 14.8% (10.2 to 27.0%) (p = 0.035), and the left median (IQR) DTF was 25.0% (18.4 to 35.0%) vs. 18.6% (9.7 to 24.2%) (p = 0.017), respectively. There was a moderate positive correlation between the LUS and the DTF (Rho = 0.3, p = 0.014). A significant increase in the LUS was observed from T-1 to T1, whereas no change was found between T1 and T2. The DTF remained stable from T-1 to T2. CONCLUSIONS: During a SBT, diaphragmatic contraction acts differently depending on the degree of pulmonary aeration. In patients with high lung aeration loss, increased diaphragmatic contractility indicates an additional respiratory effort to compensate lung volume loss that would contribute to successful SBT. Further studies are needed to evaluate the combined evaluation of lung aeration and diaphragmatic function to predict the successful weaning of patients from mechanical ventilation.

[Intergenus natural genetic transformation between Escherichia coli and Bacillus subtilis at different growth phase].

The culture fluids of Escheriachia coli with shuttle plasmid and Bacillus subtilis strains were mixed and coincubated for 40 minutes after culturing respectively in LB and minimal media. The steadily plasmid transfer by natural genetic transformation between these two gram-negative and gram-positive bacteria has been demonstrated by the methods of selective medium screening, DNase I sensitivity test and plasmid detection. In contrast to MM culture B. subtilis LB culture can be competent and has equivalent transformation frequency. Furthermore, the maximal transformation frequency was obtained when cells in exponential phase served as donors or recipients. It is suggested that B. subtilis solid transformation is different from liquid plasmid transformation including the whole process of DNA plasmid competence producing. Understanding the mechanisms of gene transfer between bacteria may aid in assessing the potential risk associated with the release of recombinant organisms into the environment.

Anticancer drug resistance of HeLa cells transfected with rat glutathione S-transferase pi gene / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To establish a cytologic expressing system of rat glutathione S-transferase pi (GST-pi) cDNA for detecting the resistance of HeLa cells to anticancer drugs.</p><p><b>METHODS</b>The assessment was made with various anticancer drugs (adriamycin, mitomycin, cisplatinum and vincristine) that showed different cytotoxicities in transfectant HeLa cells with pSV-GT containing rat GST-pi cDNA (HeLa/pSV-GT) or control pSV-neo (HeLa/pSV-neo). Expression levels of GST-pi mRNA in HeLa/pSV-GT and HeLa/pSV-neo were measured by in situ hybridization using Digoxin-labelled cDNA probe.</p><p><b>RESULTS</b>HeLa/pSV-GT expressed significantly high degree of GST-pi mRNA, whereas both HeLa/pSV-neo and HeLa cells had very low expression. Cytotoxicities of HeLa/pSV-GT and HeLa/pSV-neo with 4 anticancer drugs were measured by MTT assay. Drug concentrations for yielding 50% inhibition (IC50) in HeLa/pSV-GT by adriamycin, mitomycin and cisplatinum were 70.13 microg/mL, 10.95 microg/mL and 16.52 microg/mL, respectively. In contrast, IC50 in HeLa/pSV-neo was 10.34 microg/mL, 7.48 microg/mL and 13.70 microg/mL, respectively. The cytotoxicities of vincristine on both HeLa/pSV-GT and HeLa/pSV-neo were not significantly different.</p><p><b>CONCLUSIONS</b>Our findings suggest that HeLa/pSV-GT containing rat GST-pi cDNA is resistant to some anticancer drugs due to overexpression of GST-pi. Also, HeLa/pSV-GT cell line could serve as a useful cytogenetic model for further research.</p>