1
|
Phung TKN, Sinclair SE, Makena P, Molthen RC, Waters CM. Dynamic airway constriction in rats: heterogeneity and response to deep inspiration. Am J Physiol Lung Cell Mol Physiol 2019; 317:L39-L48. [PMID: 31017015 DOI: 10.1152/ajplung.00050.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Airway narrowing due to hyperresponsiveness severely limits gas exchange in patients with asthma. Imaging studies in humans and animals have shown that bronchoconstriction causes patchy patterns of ventilation defects throughout the lungs, and several computational models have predicted that these regions are due to constriction of smaller airways. However, these imaging approaches are often limited in their ability to capture dynamic changes in small airways, and the patterns of constriction are heterogeneous. To directly investigate regional variations in airway narrowing and the response to deep inspirations (DIs), we utilized tantalum dust and microfocal X-ray imaging of rat lungs to obtain dynamic images of airways in an intact animal model. Airway resistance was simultaneously measured using the flexiVent system. Custom-developed software was used to track changes in airway diameters up to generation 19 (~0.3-3 mm). Changes in diameter during bronchoconstriction were then measured in response to methacholine (MCh) challenge. In contrast with the model predictions, we observed significantly greater percent constriction in larger airways in response to MCh challenge. Although there was a dose-dependent increase in total respiratory resistance with MCh, the percent change in airway diameters was similar for increasing doses. A single DI following MCh caused a significant reduction in resistance but did not cause a significant increase in airway diameters. Multiple DIs did, however, cause significant increases in airway diameters. These measurements allowed us to directly quantify dynamic changes in airways during bronchoconstriction and demonstrated greater constriction in larger airways.
Collapse
Affiliation(s)
- Thien-Khoi N Phung
- Department of Physiology, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Scott E Sinclair
- Department of Physiology, University of Tennessee Health Science Center , Memphis, Tennessee.,Department of Medicine, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Patrudu Makena
- Department of Medicine, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Robert C Molthen
- Department of Medicine, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Christopher M Waters
- Department of Physiology, University of Tennessee Health Science Center , Memphis, Tennessee.,Department of Medicine, University of Tennessee Health Science Center , Memphis, Tennessee.,Department of Physiology and Saha Cardiovascular Research Center, University of Kentucky , Lexington, Kentucky
| |
Collapse
|
2
|
Hill DM, Velamuri SR, Lanfranco J, Romero Legro I, Sinclair SE, Hickerson WL. Optimization of an empiric vancomycin dosing algorithm for improved target concentration attainment in patients with thermal injury. Burns 2018; 45:423-432. [PMID: 30340863 DOI: 10.1016/j.burns.2018.09.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Revised: 08/17/2018] [Accepted: 09/13/2018] [Indexed: 10/28/2022]
Abstract
OBJECTIVE Vancomycin empirical dosing studies in thermally injured patients have netted low successful target attainment and most excluded renal dysfunction, limiting applicability. In a previous study, the authors performed a retrospective analysis of 124 patients' measured pharmacokinetic parameters to calculate optimal dose and interval for intermittent infusion regimens and find predictors of clearance and total daily dose. The objective of this study was to improve the accuracy of attaining goal therapeutic targets with initial vancomycin regimens in patients with thermal injury through retrospective modeling. METHODS In this phase 2 study, variables collected and calculated regimens in phase 1 were utilized to try and create an improved empiric vancomycin dosing algorithm in patients with thermal injury. Logistic regression was utilized to determine best predictors of dosing vancomycin every 6 and 8h. The strongest models were built as individual algorithms and tested for accuracy of target attainment. Each algorithm produced a regimen for each patient that was then tested utilizing each patient's actual measured pharmacokinetic parameters. RESULTS Univariable logistic regression of 41 variables identified 27 and 23 to be predictive of dosing every 8 or 6h, respectively. The most predictive multivariable model for dosing every 8h consisted of creatinine clearance (CrCl)≥80ml/min, Acute Kidney Injury Network classification <1, and total body surface area burned≥10 percent. For dosing every 6h, CrCl≥80ml/min, age≤40years old, days since injury≤6, and serum creatinine (SCr)≤0.8 were most predictive. Based on the top 5 multivariable models for each dosing interval, 7 algorithms were built to produce recommended regimens. The highest performing algorithm resulted in trough concentrations of <10mg/L (23%), 10-20mg/L (65%), 15-20mg/L (26%), and >20mg/L (11%); area under the concentration curve (AUC)>400mghr/L (83%); and AUC >400mghr/L without having a trough >20mg/L (72%). CONCLUSIONS The algorithm that resulted in the highest target attainment without overdosing recommended 15mg/kg dosed every 24h for CrCl≥30, every 12h for CrCl 31-79, every 8h for patients with CrCl≥80ml/min, and every 6h only if the patient with a CrCl≥80ml/min is also≤40 years old and has a SCr≤0.8. Caution is warranted for groups underrepresented in this study, such as those with very low CrCl, a low BMI, or receiving renal replacement therapy. This algorithm should be validated in other centers for patients with thermal injuries.
Collapse
Affiliation(s)
- David M Hill
- Firefighters Burn Center, Clinical Pharmacist, Department of Pharmacy, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, 881 Madison Ave, Memphis, TN 38163, USA.
| | - Sai R Velamuri
- Department of Plastic Surgery, Firefighters Regional Burn Center, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Plastic Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38103, USA.
| | - Julio Lanfranco
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| | - Ivan Romero Legro
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| | - Scott E Sinclair
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| | - William L Hickerson
- Department of Plastic Surgery, Firefighters Regional Burn Center, Regional One Health, 877 Jefferson Avenue, Memphis, TN 38103, USA; Department of Plastic Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38103, USA.
| |
Collapse
|
3
|
Hill DM, Percy MD, Velamuri SR, Lanfranco J, Romero Legro I, Sinclair SE, Hickerson WL. Predictors for Identifying Burn Sepsis and Performance vs Existing Criteria. J Burn Care Res 2018; 39:982-988. [DOI: 10.1093/jbcr/iry022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- David M Hill
- Department of Pharmacy, Firefighters Burn Center, Regional One Health, Memphis, Tennessee
- Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis
| | - Matthew D Percy
- Department of Pharmacy, Firefighters Burn Center, Regional One Health, Memphis, Tennessee
| | - Sai R Velamuri
- Department of Plastic Surgery, Firefighters Regional Burn Center, Regional One Health, Memphis, Tennessee
- Department of Plastic Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis
| | - Julio Lanfranco
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, Memphis, Tennessee
- Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis
| | - Ivan Romero Legro
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, Memphis, Tennessee
- Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis
| | - Scott E Sinclair
- Department of Medicine, Firefighters Regional Burn Center, Regional One Health, Memphis, Tennessee
- Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis
| | - William L Hickerson
- Department of Plastic Surgery, Firefighters Regional Burn Center, Regional One Health, Memphis, Tennessee
- Department of Plastic Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis
| |
Collapse
|
4
|
Aron A, Manchanda-Aron U, Sinclair SE. An African American Man in His Late 30s With Lung Cancer Presenting With Persistent Cough and Hemoptysis. Chest 2017; 152:e11-e14. [PMID: 28693782 DOI: 10.1016/j.chest.2016.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 12/01/2016] [Accepted: 12/13/2016] [Indexed: 11/28/2022] Open
Abstract
CASE PRESENTATION An African American man in his late 30s was referred to the pulmonary clinic for evaluation of a persistent cough of several weeks' duration. Cough was productive of mucopurulent sputum mixed with blood. He also noted generalized weakness and dyspnea with minimal exertion.
Collapse
Affiliation(s)
- Anirudh Aron
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Tennessee Health Science Center, Memphis, TN.
| | | | - Scott E Sinclair
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Tennessee Health Science Center, Memphis, TN
| |
Collapse
|
5
|
|
6
|
Abstract
Cannabinoids, the bioactive components of marijuana, have adverse cardiovascular consequences, including symptomatic sinus bradycardia, sinus arrest and ventricular asystole. Physicians should be aware of these deleterious consequences which can appear in otherwise healthy persons who are chronic marijuana users.
Collapse
Affiliation(s)
| | | | - Scott E Sinclair
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
| | | |
Collapse
|
7
|
Ghosh MC, Gorantla V, Makena PS, Luellen C, Sinclair SE, Schwingshackl A, Waters CM. Insulin-like growth factor-I stimulates differentiation of ATII cells to ATI-like cells through activation of Wnt5a. Am J Physiol Lung Cell Mol Physiol 2013; 305:L222-8. [PMID: 23709620 DOI: 10.1152/ajplung.00014.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Alveolar type II (ATII) epithelial cells play a crucial role in the repair and remodeling of the lung following injury. ATII cells have the capability to proliferate and differentiate into alveolar type I (ATI) cells in vivo and into an ATI-like phenotype in vitro. While previous reports indicate that the differentiation of ATII cells into ATI cells is a complex biological process, the underlying mechanism responsible for differentiation is not fully understood. To investigate factors involved in this differentiation in culture, we used a PCR array and identified several genes that were either up- or downregulated in ATI-like cells (day 6 in culture) compared with day 2 ATII cells. Insulin-like growth factor-I (IGF-I) mRNA was increased nearly eightfold. We found that IGF-I was increased in the culture media of ATI-like cells and demonstrated a significant role in the differentiation process. Treatment of ATII cells with recombinant IGF-I accelerated the differentiation process, and this effect was abrogated by the IGF-I receptor blocker PQ401. We found that Wnt5a, a member of the Wnt-Frizzled pathway, was activated during IGF-I-mediated differentiation. Both protein kinase C and β-catenin were transiently activated during transdifferentiation. Knocking down Wnt5a using small-interfering RNA abrogated the differentiation process as indicated by changes in the expression of an ATII cell marker (prosurfactant protein-C). Treatment of wounded cells with either IGF-I or Wnt5a stimulated wound closure. These results suggest that IGF-I promotes differentiation of ATII to ATI cells through the activation of a noncanonical Wnt pathway.
Collapse
Affiliation(s)
- Manik C Ghosh
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | | | | | | | | | | |
Collapse
|
8
|
Kadaria D, Sinclair SE. A case of acute agitation with a negative urine drug screen: a new wave of "legal" drugs of abuse. Tenn Med 2012; 105:31-32. [PMID: 23097956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Substance abuse is reportedly the most common cause of patients presenting with severe agitation in the emergency department. With increased access to information, people are now trying different substances for recreational use. Clinicians dealing with these patients have an increased responsibility to be aware of these new substances being abused and their management. We report a case of a 36-year-old male who was brought to the ED with severe agitation. His laboratory results, including urine drug screen, failed to suggest any substance abuse, infection or encephalopathy. Later he was found to have ingested "bath salts," which are available for purchase in gas stations and convenience stores. The patient was treated and discharged home in stable condition. We aim to raise awareness among public and medical personnel, especially physicians, about this new substance of abuse as it is not illegal yet in many states.
Collapse
Affiliation(s)
- Dipen Kadaria
- Division of Pulmonary Critical Care and Sleep Medicine, University of Tennessee Health Science Center College of Medicine, Memphis, TN, USA.
| | | |
Collapse
|
9
|
Ghosh MC, Gorantla V, Makena PS, Luellen C, Sinclair SE, Waters CM. Insulin Like Growth Factor‐1α Stimulates Differentiation of ATII Cells to ATI‐Like Cells Through Wnt5a. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.698.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Manik C Ghosh
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | - Vijay Gorantla
- MedicineUniversity of Tennessee Health Science CenterMemphisTN
| | | | | | - Scott E Sinclair
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
- MedicineUniversity of Tennessee Health Science CenterMemphisTN
| | - Christopher M Waters
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
- MedicineUniversity of Tennessee Health Science CenterMemphisTN
| |
Collapse
|
10
|
Roan E, Wilhelm K, Bada A, Makena PS, Gorantla VK, Sinclair SE, Waters CM. Hyperoxia alters the mechanical properties of alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2012; 302:L1235-41. [PMID: 22467640 DOI: 10.1152/ajplung.00223.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Patients with severe acute lung injury are frequently administered high concentrations of oxygen (>50%) during mechanical ventilation. Long-term exposure to high levels of oxygen can cause lung injury in the absence of mechanical ventilation, but the combination of the two accelerates and increases injury. Hyperoxia causes injury to cells through the generation of excessive reactive oxygen species. However, the precise mechanisms that lead to epithelial injury and the reasons for increased injury caused by mechanical ventilation are not well understood. We hypothesized that alveolar epithelial cells (AECs) may be more susceptible to injury caused by mechanical ventilation if hyperoxia alters the mechanical properties of the cells causing them to resist deformation. To test this hypothesis, we used atomic force microscopy in the indentation mode to measure the mechanical properties of cultured AECs. Exposure of AECs to hyperoxia for 24 to 48 h caused a significant increase in the elastic modulus (a measure of resistance to deformation) of both primary rat type II AECs and a cell line of mouse AECs (MLE-12). Hyperoxia also caused remodeling of both actin and microtubules. The increase in elastic modulus was blocked by treatment with cytochalasin D. Using finite element analysis, we showed that the increase in elastic modulus can lead to increased stress near the cell perimeter in the presence of stretch. We then demonstrated that cyclic stretch of hyperoxia-treated cells caused significant cell detachment. Our results suggest that exposure to hyperoxia causes structural remodeling of AECs that leads to decreased cell deformability.
Collapse
|
11
|
Kadaria D, Muthiah MP, Sinclair SE. Unusual presentations of disseminated histoplasmosis. Tenn Med 2012; 105:39-40. [PMID: 22715652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Histoplasmosis is considered to be the most prevalent endemic mycosis in United States that can present as a disseminated infection. The initial presentation of Disseminated Histoplasmosis (DH) can be atypical. We report three cases with such atypical presentation. Our first patient presented with bowel perforation, the second with left-sided pleural effusion and the third with submandibular abscess. Blood cultures as well as biopsy of perforation site, culture of pleural fluid and submandibular abscess were positive for Histoplasma Capsulatum (HC). We encourage clinicians to look for HC even in uncommon sites as dictated by the presenting symptoms and signs, especially in immunocompromised patients in endemic areas.
Collapse
Affiliation(s)
- Dipen Kadaria
- Department of Medicine at the University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| | | | | |
Collapse
|
12
|
Ghosh MC, Makena PS, Gorantla V, Sinclair SE, Waters CM. CXCR4 regulates migration of lung alveolar epithelial cells through activation of Rac1 and matrix metalloproteinase-2. Am J Physiol Lung Cell Mol Physiol 2012; 302:L846-56. [PMID: 22345572 DOI: 10.1152/ajplung.00321.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Restoration of the epithelial barrier following acute lung injury is critical for recovery of lung homeostasis. After injury, alveolar type II epithelial (ATII) cells spread and migrate to cover the denuded surface and, eventually, proliferate and differentiate into type I cells. The chemokine CXCL12, also known as stromal cell-derived factor 1α, has well-recognized roles in organogenesis, hematopoiesis, and immune responses through its binding to the chemokine receptor CXCR4. While CXCL12/CXCR4 signaling is known to be important in immune cell migration, the role of this chemokine-receptor interaction has not been studied in alveolar epithelial repair mechanisms. In this study, we demonstrated that secretion of CXCL12 was increased in the bronchoalveolar lavage of rats ventilated with an injurious tidal volume (25 ml/kg). We also found that CXCL12 secretion was increased by primary rat ATII cells and a mouse alveolar epithelial (MLE12) cell line following scratch wounding and that both types of cells express CXCR4. CXCL12 significantly increased ATII cell migration in a scratch-wound assay. When we treated cells with a specific antagonist for CXCR4, AMD-3100, cell migration was significantly inhibited. Knockdown of CXCR4 by short hairpin RNA (shRNA) caused decreased cell migration compared with cells expressing a nonspecific shRNA. Treatment with AMD-3100 decreased matrix metalloproteinase-14 expression, increased tissue inhibitor of metalloproteinase-3 expression, decreased matrix metalloproteinase-2 activity, and prevented CXCL12-induced Rac1 activation. Similar results were obtained with shRNA knockdown of CXCR4. These findings may help identify a therapeutic target for augmenting epithelial repair following acute lung injury.
Collapse
Affiliation(s)
- Manik C Ghosh
- Department of Physiology, Univ. of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | | | | | | |
Collapse
|
13
|
Makena PS, Gorantla VK, Ghosh MC, Bezawada L, Kandasamy K, Balazs L, Luellen CL, Thompson KE, Parthasarathi K, Ichijo H, Waters CM, Sinclair SE. Deletion of apoptosis signal-regulating kinase-1 prevents ventilator-induced lung injury in mice. Am J Respir Cell Mol Biol 2011; 46:461-9. [PMID: 22052879 DOI: 10.1165/rcmb.2011-0234oc] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Both hyperoxia and mechanical ventilation can independently cause lung injury. In combination, these insults produce accelerated and severe lung injury. We recently reported that pre-exposure to hyperoxia for 12 hours, followed by ventilation with large tidal volumes, induced significant lung injury and epithelial cell apoptosis compared with either stimulus alone. We also reported that such injury and apoptosis are inhibited by antioxidant treatment. In this study, we hypothesized that apoptosis signal-regulating kinase-1 (ASK-1), a redox-sensitive, mitogen-activated protein kinase kinase kinase, plays a role in lung injury and apoptosis in this model. To determine the role of ASK-1 in lung injury, the release of inflammatory mediators and apoptosis, attributable to 12 hours of hyperoxia, were followed by large tidal volume mechanical ventilation with hyperoxia. Wild-type and ASK-1 knockout mice were subjected to hyperoxia (Fi(O(2)) = 0.9) for 12 hours before 4 hours of large tidal mechanical ventilation (tidal volume = 25 μl/g) with hyperoxia, and were compared with nonventilated control mice. Lung injury, apoptosis, and cytokine release were measured. The deletion of ASK-1 significantly inhibited lung injury and apoptosis, but did not affect the release of inflammatory mediators, compared with the wild-type mice. ASK-1 is an important regulator of lung injury and apoptosis in this model. Further study is needed to determine the mechanism of lung injury and apoptosis by ASK-1 and its downstream mediators in the lung.
Collapse
Affiliation(s)
- Patrudu S Makena
- Department of Medicine, University of Tennessee Health Science Center, Memphis, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Schwingshackl A, Teng B, Ghosh M, West AN, Makena P, Gorantla V, Sinclair SE, Waters CM. Regulation and function of the two-pore-domain (K2P) potassium channel Trek-1 in alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2011; 302:L93-L102. [PMID: 21949155 DOI: 10.1152/ajplung.00078.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hyperoxia can lead to a myriad of deleterious effects in the lung including epithelial damage and diffuse inflammation. The specific mechanisms by which hyperoxia promotes these pathological changes are not completely understood. Activation of ion channels has been proposed as one of the mechanisms required for cell activation and mediator secretion. The two-pore-domain K(+) channel (K2P) Trek-1 has recently been described in lung epithelial cells, but its function remains elusive. In this study we hypothesized that hyperoxia affects expression of Trek-1 in alveolar epithelial cells and that Trek-1 is involved in regulation of cell proliferation and cytokine secretion. We found gene expression of several K2P channels in mouse alveolar epithelial cells (MLE-12), and expression of Trek-1 was significantly downregulated in cultured cells and lungs of mice exposed to hyperoxia. Similarly, proliferation cell nuclear antigen (PCNA) and Cyclin D1 expression were downregulated by exposure to hyperoxia. We developed an MLE-12 cell line deficient in Trek-1 expression using shRNA and found that Trek-1 deficiency resulted in increased cell proliferation and upregulation of PCNA but not Cyclin D1. Furthermore, IL-6 and regulated on activation normal T-expressed and presumably secreted (RANTES) secretion was decreased in Trek-1-deficient cells, whereas release of monocyte chemoattractant protein-1 was increased. Release of KC/IL-8 was not affected by Trek-1 deficiency. Overall, deficiency of Trek-1 had a more pronounced effect on mediator secretion than exposure to hyperoxia. This is the first report suggesting that the K(+) channel Trek-1 could be involved in regulation of alveolar epithelial cell proliferation and cytokine secretion, but a direct association with hyperoxia-induced changes in Trek-1 levels remains elusive.
Collapse
Affiliation(s)
- Andreas Schwingshackl
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee 38111, USA.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Makena PS, Gorantla VK, Ghosh MC, Bezawada L, Balazs L, Luellen C, Parthasarathi K, Waters CM, Sinclair SE. Lung injury caused by high tidal volume mechanical ventilation and hyperoxia is dependent on oxidant-mediated c-Jun NH2-terminal kinase activation. J Appl Physiol (1985) 2011; 111:1467-76. [PMID: 21799126 DOI: 10.1152/japplphysiol.00539.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Both prolonged exposure to hyperoxia and large tidal volume mechanical ventilation can each independently cause lung injury. However, the combined impact of these insults is poorly understood. We recently reported that preexposure to hyperoxia for 12 h, followed by ventilation with large tidal volumes, induced significant lung injury and epithelial cell apoptosis compared with either stimulus alone (Makena et al. Am J Physiol Lung Cell Mol Physiol 299: L711-L719, 2010). The upstream mechanisms of this lung injury and apoptosis have not been clearly elucidated. We hypothesized that lung injury in this model was dependent on oxidative signaling via the c-Jun NH(2)-terminal kinases (JNK). We, therefore, evaluated lung injury and apoptosis in the presence of N-acetyl-cysteine (NAC) in both mouse and cell culture models, and we provide evidence that NAC significantly inhibited lung injury and apoptosis by reducing the production of ROS, activation of JNK, and apoptosis. To confirm JNK involvement in apoptosis, cells treated with a specific JNK inhibitor, SP600125, and subjected to preexposure to hyperoxia, followed by mechanical stretch, exhibited significantly reduced evidence of apoptosis. In conclusion, lung injury and apoptosis caused by preexposure to hyperoxia, followed by high tidal volume mechanical ventilation, induces ROS-mediated activation of JNK and mitochondrial-mediated apoptosis. NAC protects lung injury and apoptosis by inhibiting ROS-mediated activation of JNK and downstream proapoptotic signaling.
Collapse
Affiliation(s)
- Patrudu S Makena
- Dept. of Medicine, Univ. of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Crosby LM, Luellen C, Zhang Z, Tague LL, Sinclair SE, Waters CM. Balance of life and death in alveolar epithelial type II cells: proliferation, apoptosis, and the effects of cyclic stretch on wound healing. Am J Physiol Lung Cell Mol Physiol 2011; 301:L536-46. [PMID: 21724858 DOI: 10.1152/ajplung.00371.2010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
After acute lung injury, repair of the alveolar epithelium occurs on a substrate undergoing cyclic mechanical deformation. While previous studies showed that mechanical stretch increased alveolar epithelial cell necrosis and apoptosis, the impact of cell death during repair was not determined. We examined epithelial repair during cyclic stretch (CS) in a scratch-wound model of primary rat alveolar type II (ATII) cells and found that CS altered the balance between proliferation and cell death. We measured cell migration, size, and density; intercellular gap formation; cell number, proliferation, and apoptosis; cytoskeletal organization; and focal adhesions in response to scratch wounding followed by CS for up to 24 h. Under static conditions, wounds were closed by 24 h, but repair was inhibited by CS. Wounding stimulated cell motility and proliferation, actin and vinculin redistribution, and focal adhesion formation at the wound edge, while CS impeded cell spreading, initiated apoptosis, stimulated cytoskeletal reorganization, and attenuated focal adhesion formation. CS also caused significant intercellular gap formation compared with static cells. Our results suggest that CS alters several mechanisms of epithelial repair and that an imbalance occurs between cell death and proliferation that must be overcome to restore the epithelial barrier.
Collapse
Affiliation(s)
- Lynn M Crosby
- Department of Physiology, University of Tennessee Health Science Center, Memphis, USA
| | | | | | | | | | | |
Collapse
|
17
|
Rapalo G, Sinclair SE, Makena P, Molthen RC, Waters CM. Dynamic Imaging of Airways During Bronchoconstriction and Deep Inspiration in Intact Rats. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.864.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
18
|
Makena PS, Luellen CL, Balazs L, Ghosh MC, Parthasarathi K, Waters CM, Sinclair SE. Preexposure to hyperoxia causes increased lung injury and epithelial apoptosis in mice ventilated with high tidal volumes. Am J Physiol Lung Cell Mol Physiol 2010; 299:L711-9. [PMID: 20833778 DOI: 10.1152/ajplung.00072.2010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Both high tidal volume mechanical ventilation (HV) and hyperoxia (HO) have been implicated in ventilator-induced lung injury. However, patients with acute lung injury are often exposed to HO before the application of mechanical ventilation. The potential priming of the lungs for subsequent injury by exposure to HO has not been extensively studied. We provide evidence that HO (90%) for 12 h followed by HV (25 μl/g) combined with HO for 2 or 4 h (HO-12h+HVHO-2h or -4h) induced severe lung injury in mice. Analysis of lung homogenates showed that lung injury was associated with cleavage of executioner caspases, caspases-3 and -7, and their downstream substrate poly(ADP-ribose) polymerase-1 (PARP-1). No significant lung injury or caspase cleavage was seen with either HO for 16 h or HV for up to 4 h. Ventilation for 4 h with HO (HVHO) did not cause significant lung injury without preexposure to HO. Twelve-hour HO followed by lower tidal volume (6 μl/g) mechanical ventilation failed to produce significant injury or caspase cleavage. We also evaluated the initiator caspases, caspases-8 and -9, to determine whether the death receptor or mitochondrial-mediated pathways were involved. Caspase-9 cleavage was observed in HO-12h+HVHO-2h and -4h as well as HO for 16 h. Caspase-8 activation was observed only in HO-12h+HVHO-4h, indicating the involvement of both pathways. Immunohistochemistry and in vitro stretch studies showed caspase cleavage in alveolar epithelial cells. In conclusion, preexposure to HO followed by HV produced severe lung injury associated with alveolar epithelial cell apoptosis.
Collapse
Affiliation(s)
- Patrudu S Makena
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | | | | | | | | | | | | |
Collapse
|
19
|
Meduri GU, Rocco PR, Annane D, Sinclair SE. Prolonged glucocorticoid treatment and secondary prevention in acute respiratory distress syndrome. Expert Rev Respir Med 2010; 4:201-10. [PMID: 20406086 DOI: 10.1586/ers.10.2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Experimental and clinical evidence has demonstrated a strong association between dysregulated systemic inflammation and progression of acute respiratory distress syndrome (ARDS). In ARDS, glucocorticoid receptor-mediated downregulation of inflammation is essential to restore homeostasis and decrease morbidity and mortality. We review the findings of eight controlled studies (n = 569) evaluating treatment initiated before day 14 of ARDS. These trials consistently reported that treatment-induced reduction in systemic inflammation was associated with a significant improvement in ratio of partial arterial oxygen tension to fraction of inspired oxygen, and reductions in multiple organ dysfunction score, duration of mechanical ventilation and intensive care unit length of stay. Treatment was also associated with a marked reduction in the risk of death (relative risk: 0.68; 95% CI: 0.56-0.81; p < 0.001) and a sizable increase in mechanical ventilation-free days (weighted mean difference: 6.58 days; 95% CI: 2.93-10.23; p < 0.001); and intensive care unit-free days (weighted mean difference: 7.02 days; 95% CI: 3.20-10.85; p < 0.001). We recommend that prolonged methylprednisolone treatment, at an initial dose of 1 mg/kg/day in early ARDS and 2 mg/kg/day in unresolving ARDS, be delivered as an infusion to avoid glycemic variability, and that infection surveillance be strictly implemented to identify infections in the absence of fever.
Collapse
Affiliation(s)
- G Umberto Meduri
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of Tennessee Health Science Center and Memphis Veterans Affairs Medical Center (111), 1030 Jefferson Avenue, Suite Room #CW444, Memphis, TN 38104, USA.
| | | | | | | |
Collapse
|
20
|
Sinclair SE, Polissar NL, Altemeier WA. Spatial distribution of sequential ventilation during mechanical ventilation of the uninjured lung: an argument for cyclical airway collapse and expansion. BMC Pulm Med 2010; 10:25. [PMID: 20444262 PMCID: PMC2888799 DOI: 10.1186/1471-2466-10-25] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 05/05/2010] [Indexed: 11/13/2022] Open
Abstract
Background Ventilator-induced lung injury (VILI) is a recognized complication of mechanical ventilation. Although the specific mechanism by which mechanical ventilation causes lung injury remains an active area of study, the application of positive end expiratory pressure (PEEP) reduces its severity. We have previously reported that VILI is spatially heterogeneous with the most severe injury in the dorsal-caudal lung. This regional injury heterogeneity was abolished by the application of PEEP = 8 cm H2O. We hypothesized that the spatial distribution of lung injury correlates with areas in which cyclical airway collapse and recruitment occurs. Methods To test this hypothesis, rabbits were mechanically ventilated in the supine posture, and regional ventilation distribution was measured under four conditions: tidal volumes (VT) of 6 and 12 ml/kg with PEEP levels of 0 and 8 cm H2O. Results We found that relative ventilation was sequentially redistributed towards dorsal-caudal lung with increasing tidal volume. This sequential ventilation redistribution was abolished with the addition of PEEP. Conclusions These results suggest that cyclical airway collapse and recruitment is regionally heterogeneous and spatially correlated with areas most susceptible to VILI.
Collapse
Affiliation(s)
- Scott E Sinclair
- Department of Medicine, University of Tennessee Health Sciences Center, 956 Court Ave E222, Memphis, TN 38163 USA.
| | | | | |
Collapse
|
21
|
|
22
|
Makena PS, Pierce SC, Chung KT, Sinclair SE. Comparative mutagenic effects of structurally similar flavonoids quercetin and taxifolin on tester strains Salmonella typhimurium TA102 and Escherichia coli WP-2 uvrA. Environ Mol Mutagen 2009; 50:451-459. [PMID: 19326464 DOI: 10.1002/em.20487] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Quercetin (QT) and Taxifolin (TF) are structurally similar plant polyphenols. Both have been reported to have therapeutic potential as anti-cancer drugs and antioxidants. Mutagenic effects of QT and TF were evaluated using Salmonella typhimurium TA102 and Escherichia coli WP-2 uvrA tester strains. Either in the presence or absence of S9 mix, QT was mutagenic to TA102 and WP2 uvrA. However, the mutagenicity of QT was significantly enhanced in the presence of S9 mix. Likewise, in the presence of Iron (Fe2+) and NADPH generating system (NGS) and absence of S9 mix, QT induced significantly high mutations in both TA102 and WP-2 uvrA. Mutagenicity of QT decreased in both strains in the presence of Iron (Fe2+) or NGS alone. TF was not mutagenic in the presence or absence of S9 mix in both TA102 and WP-2 uvrA 2, regardless of the presence of iron or NGS. Incorporation of antioxidants (ascorbate, superoxide dismutase (SOD), catalase (CAT)) and/or iron chelators (desferroxamine (DF) and ethylenediamine-tetraacetate (EDTA)) in the test systems markedly decreased QT-induced mutations in both tester strains. These results suggest that QT but not TF, could induce mutations in the presence or absence of rat liver S9 or Iron (Fe2+) and NGS in both tester strains by redox cycling and Fenton reactions to produce oxygen free radicals. Our results indicate that a minor structural variation between the two plant polyphenols could elicit a marked difference in their genotoxicities. These results provide a basis for further study into the potential use of QT in combination with iron supplements.
Collapse
Affiliation(s)
- Patrudu S Makena
- Department of Biology, The University of Memphis, Memphis, TN-38163, USA.
| | | | | | | |
Collapse
|
23
|
Sinclair SE, Chi E, Lin HI, Altemeier WA. Positive end-expiratory pressure alters the severity and spatial heterogeneity of ventilator-induced lung injury: an argument for cyclical airway collapse. J Crit Care 2008; 24:206-11. [PMID: 19327294 DOI: 10.1016/j.jcrc.2008.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Revised: 04/08/2008] [Accepted: 04/14/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE Ventilator-induced lung injury (VILI) is a recognized complication of mechanical ventilation. Although the specific mechanism by which mechanical ventilation causes lung injury remains an active area of study, both alveolar overdistension and cyclical airway collapse and recruitment have been suggested as contributing causes. We hypothesized that mechanical ventilation in the absence of positive end-expiratory pressure (PEEP) causes VILI to be more severe and regionally variable as compared with PEEP = 8 cm H(2)O. MATERIALS AND METHODS To test this hypothesis, anesthetized, supine rabbits were mechanically ventilated with an end-inspiratory pressure of 28 cm H(2)O and either 0 or 8 cm H(2)O PEEP for 4 hours. Regional lung injury was determined by histologic scoring. RESULTS In the absence of PEEP, lung injury was regionally variable and greatest in the dorsal-caudal lung. This regional injury heterogeneity was abolished by the addition of PEEP = 8 cm H(2)O. CONCLUSIONS These results suggest that VILI is regionally heterogeneous and spatially correlates with regions in which cyclical airway collapse and recruitment is most likely to occur.
Collapse
|
24
|
Waters CM, Sinclair SE, Majd S, Molthen RC. Imaging mechanical strain in small airways before and after acid injury. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.763.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Scott E. Sinclair
- Physiology
- MedicineUniversity of Tennessee Health Science CenterMemphisTN
| | - Shervin Majd
- Biomedical EngineeringUniversity of MemphisMemphisTN
| | | |
Collapse
|
25
|
Sinclair SE, Molthen RC, Haworth ST, Dawson CA, Waters CM. Airway strain during mechanical ventilation in an intact animal model. Am J Respir Crit Care Med 2007; 176:786-94. [PMID: 17626911 PMCID: PMC2020825 DOI: 10.1164/rccm.200701-088oc] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 07/10/2007] [Indexed: 01/01/2023] Open
Abstract
RATIONALE Mechanical ventilation with large tidal volumes causes ventilator-induced lung injury in animal models. Little direct evidence exists regarding the deformation of airways in vivo during mechanical ventilation, or in the presence of positive end-expiratory pressure (PEEP). OBJECTIVES To measure airway strain and to estimate airway wall tension during mechanical ventilation in an intact animal model. METHODS Sprague-Dawley rats were anesthetized and mechanically ventilated with tidal volumes of 6, 12, and 25 cm(3)/kg with and without 10-cm H(2)O PEEP. Real-time tantalum bronchograms were obtained for each condition, using microfocal X-ray imaging. Images were used to calculate circumferential and longitudinal airway strains, and on the basis of a simplified mathematical model we estimated airway wall tensions. MEASUREMENTS AND MAIN RESULTS Circumferential and longitudinal airway strains increased with increasing tidal volume. Levels of mechanical strain were heterogeneous throughout the bronchial tree. Circumferential strains were higher in smaller airways (less than 800 mum). Airway size did not influence longitudinal strain. When PEEP was applied, wall tensions increased more rapidly than did strain levels, suggesting that a "strain limit" had been reached. Airway collapse was not observed under any experimental condition. CONCLUSIONS Mechanical ventilation results in significant airway mechanical strain that is heterogeneously distributed in the uninjured lung. The magnitude of circumferential but not axial strain varies with airway diameter. Airways exhibit a "strain limit" above which an abrupt dramatic rise in wall tension is observed.
Collapse
Affiliation(s)
- Scott E Sinclair
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Nash 426, Memphis, TN 38163, USA
| | | | | | | | | |
Collapse
|
26
|
Abstract
PURPOSE OF REVIEW Hyperoxic inspired gas is essential for patients with hypoxic respiratory failure; it is also suspected, however, as a contributor to the pathogenesis of acute lung injury. Several recent studies in humans, animals, and cell culture have identified mechanisms by which hyperoxia may exert deleterious effects on critically ill patients. This review identifies relevant new findings regarding hyperoxic lung injury in the context of providing guidance for future clinical studies. RECENT FINDINGS Recent studies have clarified the roles of both receptor-mediated and mitochondrial cell death pathways in experimental hyperoxic lung injury. Studies in animals demonstrate that hyperoxia interacts with mechanical stretch to augment ventilator-induced lung injury. Finally, studies in humans implicate hyperoxia in impairment of host defense responses to infections. SUMMARY Although hyperoxia has not been conclusively identified as a clinically important cause of lung injury in humans, animal data strongly implicate it. Reports of interaction effects between hyperoxia and both mechanical ventilation and host defense suggest that clinical studies of hyperoxia must take these variables into account. Accumulating data about how hyperoxia initiates cell death provide guidance for development of both biomarkers to identify hyperoxia-induced injury and pharmacological interventions to limit hyperoxia's adverse effects.
Collapse
Affiliation(s)
- William A Altemeier
- Department of Medicine, University of Washington, Seattle, Washington 98195-6522, USA.
| | | |
Collapse
|
27
|
Desai LP, Sinclair SE, Chapman KE, Hassid A, Waters CM. High tidal volume mechanical ventilation with hyperoxia alters alveolar type II cell adhesion. Am J Physiol Lung Cell Mol Physiol 2007; 293:L769-78. [PMID: 17601798 DOI: 10.1152/ajplung.00127.2007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Patients with acute respiratory distress syndrome undergoing mechanical ventilation may be exposed to both high levels of stretch and high levels of oxygen. We hypothesized that the combination of high stretch and hyperoxia promotes loss of epithelial adhesion and impairs epithelial repair mechanisms necessary for restoration of barrier function. We utilized a model of high tidal volume mechanical ventilation (25 ml/kg) with hyperoxia (50% O(2)) in rats to investigate alveolar type II (AT2) cell adhesion and focal adhesion signaling. AT2 cells isolated from rats exposed to hyperoxia and high tidal volume mechanical ventilation (MVHO) exhibited significantly decreased cell adhesion and reduction in phosphotyrosyl levels of focal adhesion kinase (FAK) and paxillin compared with control rats, rats exposed to hyperoxia without ventilation (HO), or rats ventilated with normoxia (MV). MV alone increased phosphorylation of p130(Cas). RhoA activation was increased by MV, HO, and the combination of MV and HO. Treatment of MVHO cells with keratinocyte growth factor (KGF) for 1 h upon isolation reduced RhoA activity and restored attachment to control levels. Attachment and migration of control AT2 cells was significantly decreased by constitutively active RhoA or a kinase inactive form of FAK (FRNK), whereas expression of dominant negative RhoA in cells from MVHO-treated rats restored cell adhesion. Mechanical ventilation with hyperoxia promotes changes in focal adhesion proteins and RhoA in AT2 cells that may be deleterious for cell adhesion and migration.
Collapse
Affiliation(s)
- Leena P Desai
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | | | | | | | | |
Collapse
|
28
|
Waters CM, Desai LP, Sinclair SE, Hassid A, Chapman KE. Mechanical ventilation with hyperoxia decreases alveolar epithelial cell adhesion. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1204-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christopher M. Waters
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave., Nash 426MemphisTN38163
| | - Leena P. Desai
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave., Nash 426MemphisTN38163
| | - Scott E. Sinclair
- MedicineUniversity of Tennessee Health Science CenterColeman BuildingMemphisTN38163
| | - Aviv Hassid
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave., Nash 426MemphisTN38163
| | - Kenneth E. Chapman
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave., Nash 426MemphisTN38163
| |
Collapse
|
29
|
Sinclair SE. In Reply: Acute Hypercapnia and Gas Exchange in ARDS. Chest 2006. [DOI: 10.1016/s0012-3692(15)50933-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
30
|
Sinclair SE, Kregenow DA, Starr I, Schimmel C, Lamm WJE, Hlastala MP, Swenson ER. Therapeutic Hypercapnia and Ventilation-Perfusion Matching in Acute Lung Injury. Chest 2006; 130:85-92. [PMID: 16840387 DOI: 10.1378/chest.130.1.85] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVES Hypercapnic acidosis has antiinflammatory effects in animal models of acute lung injury (ALI) and improves ventilation-perfusion (V/Q) matching in normal lungs. The effect of hypercapnia on V/Q matching in ALI is conflicting. Hypercapnic acidosis produced by reduced tidal volumes (Vts) was associated with an increased shunt fraction (QS/QT) in patients with ALI compared with control subjects. Vt differences between groups make the assessment of hypercapnic acidosis on V/Q matching difficult. Adding CO2 to the inhaled gas allows the comparison of gas exchange under identical Vt conditions. We hypothesized the presence of hypercapnic acidosis from inspired carbon dioxide (ICD) would improve gas exchange in ALI and would be superior to that of low minute ventilation (LVe) produced by reduced respiratory rate, rather than Vt. DESIGN University laboratory study of anesthetized New Zealand White rabbits. INTERVENTIONS Assessment of V/Q relationships using the multiple inert gas elimination technique was performed in 10 saline solution-lavaged animals, which were ventilated with 6 mL/kg Vts and a positive end-expiratory pressure of 8 cm H2O. Each rabbit was studied while it was in eucapnia, followed by hypercapnia (Pa(CO2), 95 to 100 mm Hg) induced by LVe from decreased respiratory rate and by 10% ICD, in random order. MEASUREMENTS AND RESULTS The Pa(O2) was greater in ICD and LVe compared to eucapnia, but no significant differences in alveolar-arterial oxygen pressure difference or Pa(O2)/fraction of inspired oxygen ratio occurred. LVe statistically reduced the mean V/Q distributions compared with ICD and eucapnia. Log SDs of ventilation and combined retention and excretion curves of the dispersion index were both increased during LVe, indicating the presence of unfavorable changes in ventilation distribution. Neither LVe nor ICD altered the QS/QT. CONCLUSIONS LVe slightly impairs overall gas exchange and ventilation distribution, but does not increase QS/QT compared with eucapnia and ICD. While ICD does not significantly improve gas exchange, it may be superior to LVe in achieving the antiinflammatory effects of "therapeutic" hypercapnia, since it does not adversely alter gas exchange and has the potential to make the lung more uniformly acidotic.
Collapse
Affiliation(s)
- Scott E Sinclair
- Department of Medicine, University of Tennessee, 956 Court Ave, Room H314, Memphis, TN 38163, USA.
| | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
In recent years the role of neoadjuvant (primary, preoperative) chemotherapy has undergone rapid progress. Initially, neoadjuvant chemotherapy use was limited to those patients with inoperable locally advanced breast cancer in an attempt to try to down-size the tumour to make effective surgery possible. The advent of more effective chemotherapy regimens has led to an increased use of neoadjuvant therapy to shrink potentially operable tumours to allow for breast conservation when a mastectomy would have been required previously. While neoadjuvant treatment for operable tumours has indeed allowed increased rates of breast conserving surgery, it has not yet demonstrated any survival benefit over standard postoperative anthracycline-based chemotherapy. Echoing the evolution of taxane based chemotherapy from the metastatic setting through to the adjuvant situation, there has been increased interest in the role of taxanes in neoadjuvant regimens. The use of taxane-based therapies in this setting has so far shown improvements over more standard regimens in terms of clinical response rates, breast conservation, pathologic response rates, disease free survival, and overall survival. The aim of this review is to systematically summarize and interpret the results of published randomized controlled trials of neoadjuvant taxane chemotherapy for women with non-metastatic breast cancer.
Collapse
Affiliation(s)
- M Trudeau
- Toronto Sunnybrook Regional Cancer Centre, 2075 Bayview Avenue (T-Wing), Toronto, Ont., Canada M4N 3M5.
| | | | | |
Collapse
|
32
|
Chapman KE, Sinclair SE, Zhuang D, Hassid A, Desai LP, Waters CM. Cyclic mechanical strain increases reactive oxygen species production in pulmonary epithelial cells. Am J Physiol Lung Cell Mol Physiol 2005; 289:L834-41. [PMID: 15964900 DOI: 10.1152/ajplung.00069.2005] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Overdistention of lung tissue during mechanical ventilation may be one of the factors that initiates ventilator-induced lung injury (VILI). We hypothesized that cyclic mechanical stretch (CMS) of the lung epithelium is involved in the early events of VILI through the production of reactive oxygen species (ROS). Cultures of an immortalized human airway epithelial cell line (16HBE), a human alveolar type II cell line (A549), and primary cultures of rat alveolar type II cells were cyclically stretched, and the production of superoxide (O2-) was measured by dihydroethidium fluorescence. CMS stimulated increased production of O2- after 2 h in each type of cell. 16HBE cells exhibited no significant stimulation of ROS before 2 h of CMS (20% strain, 30 cycles/min), and ROS production returned to control levels after 24 h. Oxidation of glutathione (GSH), a cellular antioxidant, increased with CMS as measured by a decrease in the ratio of the reduced GSH level to the oxidized GSH level. Strain levels of 10% did not increase O2- production in 16HBE cells, whereas 15, 20, and 30% significantly increased generation of O2-. Rotenone, a mitochondrial complex I inhibitor, partially abrogated the stretch-induced generation of O2- after 2 h CMS in 16HBE cells. NADPH oxidase activity was increased after 2 h of CMS, contributing to the production of O2-. Increased ROS production in lung epithelial cells in response to elevated stretch may contribute to the onset of VILI.
Collapse
Affiliation(s)
- Kenneth E Chapman
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
| | | | | | | | | | | |
Collapse
|
33
|
Abstract
OBJECTIVE Mechanical overdistension and hyperoxia can independently cause lung injury, yet little is known about their combined effects. We hypothesized that hyperoxia exacerbates lung injury caused by large tidal volume ventilation. DESIGN Experimental study. SETTING University laboratory. SUBJECTS Anesthetized, paralyzed rabbits. INTERVENTIONS In experiment 1, 12 rabbits were ventilated with 25 mL/kg tidal volumes at positive end-expiratory pressure of 0 cm H2O for 4 hrs with either hyperoxia (HO; FiO2 = 0.5) or normoxia (NO; FiO2 = 0.21). In experiment 2, a separate group of animals were randomized to one of four groups to assess the interaction of tidal volume and inspired oxygen concentration on potential mediators of injury after 2 hrs of ventilation, before significant injury occurs: a) NO+normal tidal volume (NV; VT = 10 mL/kg); b) HO+NV; c) NO+high tidal volume (HV; VT = 25 mL/kg); d) HO+HV (n = 3 per group). MEASUREMENTS AND MAIN RESULTS : In the first study, HO compared with the NO group had significantly reduced PaO2/FiO2 ratio (320 +/- 110 vs. 498 +/- 98, p = .014) and increased lung injury scores at 4 hrs. Hyperoxia also significantly increased polymorphonuclear leukocytes, growth-related oncogene-alpha (2073 +/- 535 vs. 463 +/- 236 pg/mL, p = .02), and monocyte chemotactic protein-1 (7517 +/- 1612 vs. 2983 +/- 1289 pg/mL, p = .05) concentrations in bronchoalveolar lavage fluid. The second study showed increased alveolar-capillary permeability to a 70-kD fluorescent-labeled dextran only in response to the combination of both HO and HV. Chemokines and bronchoalveolar lavage fluid neutrophils were elevated in both HV groups; however, hyperoxia did not further increase chemokine or neutrophil counts over normoxia. No difference in lipid peroxidation was seen between groups. CONCLUSIONS Moderate hyperoxia exacerbates lung injury in a large tidal volume model of ventilator-induced lung injury. The mechanism by which this occurs is not mediated by increased production of CXC chemokines or lipid peroxidation.
Collapse
Affiliation(s)
- Scott E Sinclair
- Departments of Medicine and Physiology, University of Tennessee, Memphis, TN 38163, USA.
| | | | | | | |
Collapse
|
34
|
Sinclair SE, Kregenow DA, Lamm WJE, Starr IR, Chi EY, Hlastala MP. Hypercapnic acidosis is protective in an in vivo model of ventilator-induced lung injury. Am J Respir Crit Care Med 2002; 166:403-8. [PMID: 12153979 DOI: 10.1164/rccm.200112-117oc] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To investigate whether hypercapnic acidosis protects against ventilator-induced lung injury (VILI) in vivo, we subjected 12 anesthetized, paralyzed rabbits to high tidal volume ventilation (25 cc/kg) at 32 breaths per minute and zero positive end-expiratory pressure for 4 hours. Each rabbit was randomized to receive either an FI(CO(2)) to achieve eucapnia (Pa(CO(2)) approximately 40 mm Hg; n = 6) or hypercapnic acidosis (Pa(CO(2)) 80-100 mm Hg; n = 6). Injury was assessed by measuring differences between the two groups' respiratory mechanics, gas exchange, wet:dry weight, bronchoalveolar lavage fluid protein concentration and cell count, and injury score. The eucapnic group showed significantly higher plateau pressures (27.0 +/- 2.5 versus 20.9 +/- 3.0; p = 0.016), change in Pa(O(2)) (165.2 +/- 19.4 versus 77.3 +/- 87.9 mm Hg; p = 0.02), wet:dry weight (9.7 +/- 2.3 versus 6.6 +/- 1.8; p = 0.04), bronchoalveolar lavage protein concentration (1,350 +/- 228 versus 656 +/- 511 micro g/ml; p = 0.03), cell count (6.86 x 10(5) +/- 0.18 x 10(5) versus 2.84 x 10(5) +/- 0.28 x 10(5) nucleated cells/ml; p = 0.021), and injury score (7.0 +/- 3.3 versus 0.7 +/- 0.9; p < 0.0001). We conclude that hypercapnic acidosis is protective against VILI in this model.
Collapse
Affiliation(s)
- Scott E Sinclair
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Washington, BB-1253 HSB Box 356522, Seattle, WA 98195-6522, USA.
| | | | | | | | | | | |
Collapse
|
35
|
Kreck TC, Krueger MA, Altemeier WA, Sinclair SE, Robertson HT, Shade ED, Hildebrandt J, Lamm WJ, Frazer DA, Polissar NL, Hlastala MP. Determination of regional ventilation and perfusion in the lung using xenon and computed tomography. J Appl Physiol (1985) 2001; 91:1741-9. [PMID: 11568158 DOI: 10.1152/jappl.2001.91.4.1741] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We propose a model to measure both regional ventilation (V) and perfusion (Q) in which the regional radiodensity (RD) in the lung during xenon (Xe) washin is a function of regional V (increasing RD) and Q (decreasing RD). We studied five anesthetized, paralyzed, mechanically ventilated, supine sheep. Four 2.5-mm-thick computed tomography (CT) images were simultaneously acquired immediately cephalad to the diaphragm at end inspiration for each breath during 3 min of Xe breathing. Observed changes in RD during Xe washin were used to determine regional V and Q. For 16 mm(3), Q displayed more variance than V: the coefficient of variance of Q (CV(Q)) = 1.58 +/- 0.23, the CV of V (CV(V)) = 0.46 +/- 0.07, and the ratio of CV(Q) to CV(V) = 3.5 +/- 1.1. CV(Q) (1.21 +/- 0.37) and the ratio of CV(Q) to CV(V) (2.4 +/- 1.2) were smaller at 1,000-mm(3) scale, but CV(V) (0.53 +/- 0.09) was not. V/Q distributions also displayed scale dependence: log SD of V and log SD of Q were 0.79 +/- 0.05 and 0.85 +/- 0.10 for 16-mm(3) and 0.69 +/- 0.20 and 0.67 +/- 0.10 for 1,000-mm(3) regions of lung, respectively. V and Q measurements made with CT and Xe also demonstrate vertically oriented and isogravitational heterogeneity, which are described using other methodologies. Sequential images acquired by CT during Xe breathing can be used to determine both regional V and Q noninvasively with high spatial resolution.
Collapse
Affiliation(s)
- T C Kreck
- Department of Medicine, University of Washington, Seattle, WA 98195-6522, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Sinclair SE, Frighetto L, Loewen PS, Sunderji R, Teal P, Fagan SC, Marra CA. Cost-Utility analysis of tissue plasminogen activator therapy for acute ischaemic stroke: a Canadian healthcare perspective. Pharmacoeconomics 2001; 19:927-936. [PMID: 11700779 DOI: 10.2165/00019053-200119090-00004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
BACKGROUND There are over 40000 ischaemic strokes annually in Canada, which result in significant morbidity, mortality and burden to the healthcare system. A recent, large clinical trial has evaluated tissue plasminogen activator (t-PA) intravenously for the treatment of acute ischaemic stroke with promising outcomes but with an increased risk of symptomatic intracranial haemorrhage. OBJECTIVE To compare clinical and economic outcomes of intravenous t-PA therapy (0.9 mg/kg, to a maximum of 90 mg, initiated within 3 hours of stroke onset) versus no t-PA for acute ischaemic stroke based on the outcomes achieved in the National Institute of Neurological Disorders and Stroke (NINDS) trial. DESIGN A Markov model depicting the natural lifetime course after an initial acute ischaemic stroke. On the basis of this model, a simulated trial compared no t-PA with t-PA. PATIENTS A hypothetical cohort of 1000 patients with acute ischaemic stroke. STUDY PERSPECTIVE Canadian healthcare system. OUTCOME MEASURES Total acute stroke and post-stroke treatment costs and cumulative quality-adjusted life-years (QALYs). RESULTS For a hypothetical cohort of 1000 patients, the estimated lifetime stroke costs were 103100000 Canadian dollars (SCan) [1999 values) in the t-PA arm ($Can103100 per patient) compared with SCan106900000 in the no t-PA arm ($Can106900 per patient), yielding a lifetime cost difference of $Can3800000 in favour of t-PA versus no t-PA (SCan3800 per patient). In the hypothetical cohort, t-PA treatment resulted in 13 130 QALYs versus 9670 QALYs with no t-PA treatment. This translated into a net benefit of 3460 additional QALYs per 1000 patients (3.46 QALYs per patient). No treatment, outcome or economic variables influenced the model outcome. CONCLUSION From the standpoint of cost effectiveness, treatment of acute ischaemic stroke with intravenous t-PA is an economically attractive strategy.
Collapse
Affiliation(s)
- S E Sinclair
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
| | | | | | | | | | | | | |
Collapse
|
37
|
Chornuk MA, Bernard SL, Burns JW, Glenny RW, Sheriff DD, Sinclair SE, Polissar NL, Hlastala MP. Effects of inertial load and countermeasures on the distribution of pulmonary blood flow. J Appl Physiol (1985) 2000; 89:445-57. [PMID: 10926625 DOI: 10.1152/jappl.2000.89.2.445] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We assessed the influence of cranial-to-caudal inertial force (+G(z)) and the countermeasures of anti-G suit and positive pressure breathing during G (PBG), specifically during +G(z), on regional pulmonary blood flow distribution. Unanesthetized swine were exposed randomly to 0 G(z) (resting), +3 G(z), +6 G(z), and +9 G(z), with and without anti-G suit and PBG with the use of the Air Force Research Laboratory centrifuge at Brooks Air Force Base (the gravitational force of the Earth, that is, the dorsal-to-ventral inertial force, was present for all runs). Fluorescent microspheres were injected into the pulmonary vasculature as a marker of regional pulmonary blood flow. Lungs were excised, dried, and diced into approximately 2-cm(3) pieces, and the fluorescence of each piece was measured. As +G(z) was increased from 0 to +3 G(z), blood flow shifted from cranial and hilar regions toward caudal and peripheral regions of the lung. This redistribution shifted back toward cranial and hilar regions as anti-G suit inflation pressure increased at +6 and +9 G(z). Perfusion heterogeneity increased with +G(z) stress and decreased at the higher anti-G suit pressures. The distribution of pulmonary blood flow was not affected by PBG. ANOVA indicated anatomic structure as the major determinant of pulmonary blood flow.
Collapse
Affiliation(s)
- M A Chornuk
- Department of Physiology and Biophysics, University of Washington, Seattle 98195, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Sinclair SE, McKinney S, Glenny RW, Bernard SL, Hlastala MP. Exercise alters fractal dimension and spatial correlation of pulmonary blood flow in the horse. J Appl Physiol (1985) 2000; 88:2269-78. [PMID: 10846045 DOI: 10.1152/jappl.2000.88.6.2269] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We determined the changes in fractal dimensions and spatial correlations of regional pulmonary blood flow with increasing exercise in race horses (n = 4) by using 15-microm fluorescent microspheres. Fluorescence was measured to quantitate regional blood to 1.3-cm(3) samples (n = 1,621-2,503). Perfusion distributions were characterized with fractal dimensions (a measure of spatial variability) and spatial correlations. On average, the fractal dimension decreased with exercise (trot 1.216 to gallop 1.173; P < 0. 05) despite a variable fractal dimension at rest. Spatial correlation of flow to neighboring pieces increased with exercise (trot 0.57 +/- 0.074 to gallop 0.73 +/- 0.051) and was inversely correlated with fractal dimension, indicating better spatial correlation as blood flow distribution becomes more uniform. This is the first study to document a change in fractal dimension as a result of increasing pulmonary blood flow. Spatial differences in response to vasoregulatory mediators may play a role in this phenomenon.
Collapse
Affiliation(s)
- S E Sinclair
- Department of Medicine, University of Washington, Seattle 98195-6522, USA.
| | | | | | | | | |
Collapse
|
39
|
Affiliation(s)
- S E Sinclair
- Pulmonary and Critical Care Medicine, University of Washington Medical Center, Seattle 98195-6522, USA
| | | |
Collapse
|
40
|
|
41
|
Martin FG, Sinclair SE. The "prevailing fee" concept and Medicare. Pa Med 1966; 69:40-1 passim. [PMID: 5938873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
42
|
Sinclair SE. Tiger by the tail. Pa Med J 1966; 69:56-7. [PMID: 10359623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
|