Lung adenocarcinoma cells treated for 16 h with trichostatin A (TSA), an inhibitor of histone deacetylases, and untreated cells were analyzed with respect to differential gene expression. Complex hybridization of cDNA arrays revealed repression of Bcl-xL, CRAB2 and TFIID/TAFII31 as well as induction of p21waf1/cip1, GATA-2, hsp86, ID1, ID2 and ID3 mRNA expression, which could be verified by Northern blotting. ID2 induction was further confirmed by Taqman realtime quantitative RT-PCR. The described alterations of gene expression due to TSA renders the lung adenocarcinoma cells susceptible to induction of apoptosis.
Background
Non-invasive ventilation (NIV) is a recommended treatment for COPD patients suffering from chronic hypercapnic respiratory failure. Prolonged dyspnea after mask removal in the morning, often referred to as deventilation syndrome, is a common side effect but has been poorly characterized yet. This study aimed to explore the pathomechanism, identify risk factors and possible treatment strategies for the deventilation syndrome.
Methods
A prospective, controlled, non-blinded study was conducted. After a night with established NIV therapy, the patients underwent spirometry, blood gas analyses and 6-min walking tests (6MWT) directly, at 2 and 4 h after mask removal. Dyspnea was measured by the modified Borg scale. Bodyplethysmography and health-related quality of life (HRQoL) questionnaires were used. Patients suffering from deventilation syndrome (defined as dyspnea of at least three points on the Borg scale after mask removal) were treated with non-invasive pursed lip breathing ventilation (PLBV) during the second night of the study.
Results
Eleven of 31 patients included (35%) met the given criteria for a deventilation syndrome. They reported significantly more dyspnea on the Borg scale directly after mask removal (mean: 7.2 ± 1.0) compared to measurement after 2 h (4.8 ± 2.6; p = 0.003). Initially, mean inspiratory vital capacity was significantly reduced (VCmax: 46 ± 16%) compared to 2 h later (54 ± 15%; p = 0.002), while no changes in pulse oximetry or blood gas analysis were observed. Patients who suffered from a deventilation syndrome had a significantly higher mean airway resistance (Reff: 320 ± 88.5%) than the patients in the control group (253 ± 147%; p = 0.021). They also scored significantly lower on the Severe Respiratory Insufficiency Questionnaire (SRI; mean: 37.6 ± 10.1 vs 50.6 ± 16.7, p = 0.027). After one night of ventilation in PLBV mode, mean morning dyspnea decreased significantly to 5.6 ± 2.0 compared to 7.2 ± 1.0 after established treatment (p = 0.019) and mean inspiratory vital capacity increased from 44 ± 16.0% to 48 ± 16.3 (p = 0.040).
Conclusions
The deventilation syndrome is a serious side effect of NIV in COPD patients, characterized by increase of dyspnea. It is associated with decrease in vital capacity, exercise tolerance after mask removal and lower HRQoL. Patients with high airway resistance are at greater risk of suffering from morning dyspnea. Ventilation in PLBV mode may prevent or improve the deventilation syndrome.
Trial registration: The study was registered in the German Clinical Trials Register (DRKS00016941) on 09 April 2019.
Long-term non-invasive ventilation (NIV) is recommended for patients with stable chronic obstructive lung disease (COPD) and chronic hypercapnia. High inspiratory pressure NIV (hiNIV) and a significant reduction of arterial pCO 2 have been shown to prolong survival. Often, patients on hiNIV describe severe respiratory distress, known as "deventilation syndrome", after removal of the NIV mask in the morning. Mechanical pursed lips breathing ventilation (PLBV) is a new non-invasive ventilation mode that mimics the pressure-curve of pursed lips breathing during expiration. The clinical impact of switching patients from standard NIV to PLBV has not been studied so far. Patients and methods In this hypothesis generating study, we retrospectively analysed the effects of switching COPD patients (stage GOLD III-IV) from conventional NIV to PLBV. Medical records of all patients who had an established NIV and were switched to PLBV between March 2016 and October 2017 were screened. Patients were included if they complained of shortness of breath on mask removal, used their conventional NIV regularly, and had a documented complete diagnostic workup including lung function testing, blood gas analysis and 6-minute walk test (6MWT) before and after 3-7 days of PLBV. Results Six male and 10 female patients (median age 65.4 years; IQR 64.0-71.3) with a previous NIV treatment duration of 38 months (median; IQR 20-42) were analysed. After PLVB initiation, the median inspiratory ventilation pressure needed to maintain the capillary pre-switch
Recently we described a new signal transduction-based tumor therapeutic strategy involving first sensitization of tumor cells by trichostatin A (TSA), an inhibitor of histone deacetylation, and thereafter efficient apoptotic triggering by ribotoxic agents, which activate stress-activated protein kinases. In the present work we investigate the molecular basis of the sensitization step in this therapeutic model system and describe TSA-induced changes in mRNA and protein expression of several candidate genes identified previously by complex hybridization. Furthermore, activities of 15 different protein kinases were followed after TSA application, using a new filter-based technique (PhosphoSpots-Assay). The obtained data suggest that TSA induces pro-apoptotic genes like ID1, ID2, ID3, and down-regulates anti-apoptotic genes like Hsp27 and Bcl-xL, thereby shifting the cellular equilibrium from life to death. Furthermore, activities of calcium/calmodulin-dependent kinase II and protein kinase C, which have been assigned pro-apoptotic function in other systems, are induced.
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