Biomedical subjects

Dries Testelmans

Publications and source records attributed to Dries Testelmans.

3 recordsLinked to original sources

PubMed2006

Rocuronium exacerbates mechanical ventilation-induced diaphragm dysfunction in rats.

OBJECTIVE: Nondepolarizing neuromuscular blocking agents are commonly used in the intensive care setting, but they have occasionally been associated with development of myopathy. In addition, diaphragmatic atrophy and a reduction in diaphragmatic force were reported after short-term controlled mechanical ventilation in animal models. We hypothesized that infusion of rocuronium, an aminosteroidal neuromuscular blocking agent, during 24 hrs of controlled mechanical ventilation would further alter diaphragm function and would enhance activation of the ubiquitin- proteasome pathway. DESIGN: Randomized, controlled experiment. SETTING: Basic animal science laboratory. SUBJECTS: Male Wistar rats, 14 wks old. INTERVENTIONS: Rats were divided into four groups: a control group, a group of anesthetized rats breathing spontaneously for 24 hrs, and two groups submitted to mechanical ventilation for 24 hrs, receiving a continuous infusion of either 0.9% NaCl or rocuronium. MEASUREMENTS AND MAIN RESULTS: In vitro diaphragm force was decreased more significantly after 24 hrs of mechanical ventilation combined with rocuronium infusion than after mechanical ventilation alone (e.g., tetanic force, -27%; p < .001 vs. mechanical ventilation). Similarly, the decrease in diaphragm type IIx/b fiber dimensions was more pronounced after mechanical ventilation with rocuronium treatment than with saline treatment (-38% and -29%, respectively; p < .001 vs. control). Diaphragm hydroperoxide levels increased similarly in both mechanically ventilated groups. Diaphragm muscle RING-finger protein-1 (MURF-1) messenger RNA expression, an E3 ligase of the ubiquitin-proteasome pathway, increased after mechanical ventilation (+212%, p < .001 vs. control) and increased further with combination of rocuronium (+320%, p < .001 vs. control). Significant correlations were found between expression of MURF-1 messenger RNA, diaphragm force, and type IIx/b fiber dimensions. CONCLUSIONS: Infusion of rocuronium during controlled mechanical ventilation leads to further deterioration of diaphragm function, additional atrophy of type IIx/b fibers, and an increase in MURF-1 messenger RNA in the diaphragm, which suggests an activation of the ubiquitin-proteasome pathway. These findings could be important with regard to weaning failure in patients receiving this drug for prolonged periods in the intensive care unit setting.

Androstanols↗

PubMed2005

Intermittent spontaneous breathing protects the rat diaphragm from mechanical ventilation effects.

OBJECTIVE: Short-term mechanical ventilation has been proven to reduce diaphragm force and fiber dimensions. We hypothesized that intermittent spontaneous breathing during the course of mechanical ventilation would minimize the effects of mechanical ventilation on diaphragm force and expression levels of transcription factors (MyoD and myogenin). DESIGN: Randomized, controlled experiment. SETTING: Animal basic science laboratory. SUBJECTS: Male Wistar rats, weighing 350-500 g. INTERVENTIONS: Anesthetized and tracheotomized rats were submitted to either 24 hrs of spontaneous breathing (SB, n = 5), 24 hrs of continuous controlled mechanical ventilation (CMV, n = 7), or controlled mechanical ventilation with intermittent spontaneous breathing: 60 mins every 5 hrs of mechanical ventilation repeated four times (ISB60, n = 8) or 5 mins every 5 hrs 55 mins of mechanical ventilation repeated four times (SB5, n = 9). They were compared with control animals free from intervention (C, n = 5). MEASUREMENTS AND MAIN RESULTS: The profile of the diaphragm force-frequency curve of the controls and SB group was significantly different from that of the ISB and CMV groups; especially, the mean asymptotic force was less in the ISB and CMV compared with controls and SB. CMV resulted in a significant decrease in the diaphragm type I (-26%, p < .05 vs. C) and type IIx/b (-39%, p < .005 vs. C and SB) cross-sectional area, whereas this was not observed in the ISB groups. Diaphragm MyoD protein expression was significantly decreased after ISB60 (-35%, p < .0001 vs. C and SB) and even more after CMV (-73%, p < .0001 vs. others). The same pattern was observed with myogenin protein levels. Positive relationships between diaphragm MyoD and myogenin protein levels and diaphragm force were observed. CONCLUSIONS: The data demonstrated that intermittent spontaneous breathing during the course of mechanical ventilation may minimize the deleterious effect of controlled mechanical ventilation on diaphragm force, fiber dimensions, and expression of transcription factors.

Animals↗

PubMed2003

Early changes in rat diaphragm biology with mechanical ventilation.

To better characterize the effects of 24-hour mechanical ventilation on diaphragm, the expression of myogenic transcription factors, myosin heavy chains, and sarcoplasmic/endoplasmic reticulum calcium-ATPase pumps was examined in rats. In the diaphragm of mechanically ventilated animals, the mRNA of MyoD, myosin heavy chain-2a and -2b, and sarcoplasmic/endoplasmic reticulum calcium-ATPase-1a decreased, whereas myogenin mRNA increased. In the diaphragm of anesthetized and spontaneously breathing rats, only the mRNA of MyoD and myosin heavy chain-2a decreased. MyoD and myogenin protein expression followed the changes at the mRNA, whereas the myosin heavy chain isoforms did not change. Parallel experiments involving the gastrocnemius were performed to assess the relative contribution of muscle shortening versus immobilization-induced deconditioning on muscle regulatory factor expression. Passive shortening produced no additional effects compared with immobilization-induced deconditioning. The overall changes followed a remarkably similar pattern except for MyoD protein expression, which increased in the gastrocnemius and decreased in the diaphragm while its mRNA diminished in both muscles. The early alterations in the expression of muscle protein and regulatory factors may serve as underlying molecular basis for the impaired diaphragm function seen after 24 hours of mechanical ventilation. Whether immobilization-induced deconditioning and/or passive shortening play a role in these alterations could not be fully unraveled.

Animals↗