Browsing by Subject "Respiration"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item A Method for Real-Time Assessment of Mitochondrial Respiration Using Murine Corneal Biopsy(Association for Research in Vision and Ophthalmology, 2023-08-29) Liang, Wentao; Huang, Li; Yuan, Tian; Cheng, Rui; Takahashi, Yusuke; Moiseyev, Gennadiy P.; Karamichos, Dimitrios; Ma, Jian-XingPURPOSE: To develop and optimize a method to monitor real-time mitochondrial function by measuring the oxygen consumption rate (OCR) in murine corneal biopsy punches with a Seahorse extracellular flux analyzer. METHODS: Murine corneal biopsies were obtained using a biopsy punch immediately after euthanasia. The corneal metabolic profile was assessed using a Seahorse XFe96 pro analyzer, and mitochondrial respiration was analyzed with specific settings. RESULTS: Real-time adenosine triphosphate rate assay showed that mitochondrial oxidative phosphorylation is a major source of adenosine triphosphate production in ex vivo live murine corneal biopsies. Euthanasia methods (carbon dioxide asphyxiation vs. overdosing on anesthetic drugs) did not affect corneal OCR values. Mouse corneal biopsy punches in 1.5-mm diameter generated higher and more reproducible OCR values than those in 1.0-mm diameter. The biopsy punches from the central and off-central cornea did not show significant differences in OCR values. There was no difference in OCR reading by the tissue orientations (the epithelium side up vs. the endothelium side up). No significant differences were found in corneal OCR levels between sexes, strains (C57BL/6J vs. BALB/cJ), or ages (4, 8, and 32 weeks). Using this method, we showed that the wound healing process in the mouse cornea affected mitochondrial activity. CONCLUSIONS: The present study validated a new strategy to measure real-time mitochondrial function in fresh mouse corneal tissues. This procedure should be helpful for studies of the ex vivo live corneal metabolism in response to genetic manipulations, disease conditions, or pharmacological treatments in mouse models.Item Investigating the Use of Resistance Breathing for the Detection of Acute Hypovolemia(2021-05) Rusy, Ryan; Rickards, Caroline A.; Goulopoulou, Styliani; Mallet, Robert T.; Olivencia-Yurvati, Albert H.Introduction: Standard vital signs (e.g., heart rate and blood pressure) lack sensitivity and specificity to detect blood volume status following hemorrhage. Inspiratory resistance breathing has therapeutic potential to increase blood pressure and cardiac output following blood loss. We investigated the potential utility of resistance breathing as a novel method to detect volume loss. We hypothesized that resistance breathing would elicit greater increases in absolute and breath-to-breath amplitude of stroke volume and arterial pressure under hypovolemic vs. normovolemic conditions. Methods: Data were retrospectively analyzed from 23 healthy human subjects aged 23-40 years. Subjects underwent lower body negative pressure (LBNP) protocols to simulate hemorrhage with and without resistance breathing (via an impedance threshold device, ITD). Continuous arterial pressure and stroke volume were measured via finger photoplethysmography. Comparisons of absolute and changes in the breath-to-breath amplitude of arterial pressure and stroke volume were made under 4 conditions: 1) normovolemia; 2) normovolemia + resistance breathing; 3) hypovolemia, and; 4) hypovolemia + resistance breathing. The sensitivity and specificity of breath-to-breath arterial pressure and stroke volume amplitude responses in distinguishing between normovolemia and hypovolemia were assessed via area under the curve (AUC) of receiver operating characteristic (ROC) curves. Results: With resistance breathing the amplitude of systolic arterial pressure (P=0.007), diastolic arterial pressure (P<0.001), and mean arterial pressure (P<0.001) increased during hypovolemia vs. normovolemia, and the amplitude of stroke volume decreased (P=0.002). In distinguishing between normovolemia and hypovolemia, the ROC AUC were >0.86 for breath-by-breath mean, maximum and minimum stroke volume responses, and 0.77 for the amplitude response. The ROC AUC for mean arterial pressure amplitude was 0.88, and 0.64, 0.54, and 0.72 for the mean, maximum and minimum responses. Conclusions: The dynamic responses of arterial pressure and stroke volume with resistance breathing during hypovolemia show promise as a diagnostic tool for detection of hypovolemia in humans.