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Abstract

Objective To examine the effects of short-term cyclic stretch on apoptosis in alveolar type II cells (A549). To study in vitro the direct influence of alveolar type II cells on mechanical stretch. Methods A549 were treated with different doses of lipopolysaccharide (LPS), 0 ng/ml, 1 ng/ml, 10 ng/ml, 100 ng/ml, 1000 ng/ml, and then A549 were lengthened 5%, 15%, 30% using a FLEXCELL tension unit 4000, a vacuum-driven device that applies strain to cells, which were cultured in six-well plates coated with collagen-I, and 12 cycles/min for 4 hours. Apoptosis was measured using the flow cytometry method that measures annexin V and propidium iodide (PI) staining. The morphological changes of apoptotic cells were observed by transmission electron microscope. Results Apoptosis could be induced in alveolar type II cells (A549) by mechanical stretch. The percentage of annexin V + PI cells increased after being treated with cyclic stretch for 4 hours by 5%, 15%, 30% in all groups. The morphological features of apoptotic cells demonstrated by transmission electron microscope were as follows: shrinkage of the cell, chromatin condensation and aggregation under the nuclear membrane as a crescent or lump, membrane-encapsulated nuclear fragment or cell organ formed by invagination of the cell membrane, and apoptotic body formation followed by vacuolization. Conclusion Apoptosis induced by mechanical stretch and LPS is dose dependent. Mechanical stretch aggravates apoptosis especially in cells treated with LPS. Annexin V and PI double staining is a specific, sensitive, and quantitative method for analyzing apoptotic cells. It is also helpful to clarify the protective mechanism of low-volume ventilation in ARDS. Acknowledgement The study was funded by the 'One Hundred People' project of Shanghai Sanitary Bureau (03-77-20). Introduction Although extrapulmonary ALI/ARDS is a common clinical entity, most animal models used to study this disease are induced by direct lung injuries. Our intention was therefore to investigate whether a condition resembling ALI/ARDS develops during the course of a fecal peritonitis in pigs; in that case experimental peritonitis would also prove as a clinically relevant ARDS model. Methods In 10 anesthetized, mechanically ventilated, and instrumented pigs fecal peritonitis was induced by inoculating autologue feces pellets suspended in saline. Mechanical ventilation was set with VT = 8 ml/kg, FiO 2 to reach a SaO 2 target of >90%, PEEP = 10 cmH 2 O if PaO 2 /FiO 2 > 300 and 12 cmH 2 O if PaO 2 /FiO 2 < 300, and respiratory rate to obtain a PaCO 2 of 35-45 mmHg. Before as well as 12 and 24 hours after peritonitis induction we measured the PaO 2 /FiO 2 ratio, the total compliance of the respiratory system (C), calculated as VT/(P plateau -PEEP) and inspiratory airway resistance (R i ) calculated as (P max -P plateau ) / mean inspiratory flow. Data are mean [range]. Results For data see Table 1. During the course of the 24-hour study period, six of 10 animals developed gas exchange deteriorations consistent w...

Peritoneal Oxygenation as a Novel Technique for Extrapulmonary Ventilation; A Review and Discussion of the Literature

“…Peritoneal oxygenation has been evaluated in an ARDS-swine model by Lemus et al [ 12 ]. The study was conducted on four swine, which were invasively monitored for eight hours while under anaesthesia.…”

“…After five hours, oleic acid was administered via the pulmonary circulation to induce ARDS, which was later confirmed by histopathology. PEROX maintained normal oxygenation indices both before and after the outset of ARDS; there was no statistically significant difference in oxygenation before or after ARDS [ 12 ]. Although this study would appear to demonstrate efficacy for the PEROX continuous oxygenation model, there is only limited methodology and reporting available, and it has not been replicated, so it should be treated with some caution.…”

“… Wang et al (2014) [ 11 ] Swine [ n = 36] FiO 2 progressively reduced N/A Peritoneal jet ventilation Duration of safe apnoea increased, an increased frequency of jet ventilation, the longest safe apnoea duration in the groups at a frequency of 80–120 times a minute. Lemus et al (2006) [ 12 ] Swine [ n = 4] ARDS Oleic acid administered to pulmonary circulation PEROX PEROX maintained normal oxygenation indices both prior to and following the outset of ARDS; there was no statistically significant difference in oxygenation prior to or following ARDS. Feshitan et al (2014) [ 14 ] Rat [ n = 16] Pneumothorax N/A Phospholipid-coated OMBs via PMO given as an intraperitoneal infusion Group receiving OMBs had a 100% two-hour survival, the oxygenated saline and those who were untreated had a mean survival of 15.5 ± 8.1 min and 16.0 ± 4.8 min, respectively ( p < 0.004).…”