Martina Nowak

Publications (6)55.09 Total impact

• Article: Deletion of CD39 on natural killer cells attenuates hepatic ischemia/reperfusion injury in mice.

  Guido Beldi, Yara Banz, Alexander Kroemer, Xiaofeng Sun, Yan Wu, Nadine Graubardt, Alyssa Rellstab, Martina Nowak, Keiichi Enjyoji, Xian Li, Wolfgang G Junger, Daniel Candinas, Simon C Robson
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  ABSTRACT: Natural killer (NK) cells play crucial roles in innate immunity and express CD39 (Ecto-nucleoside triphosphate diphosphohydrolase 1 [E-NTPD1]), a rate-limiting ectonucleotidase in the phosphohydrolysis of extracellular nucleotides to adenosine. We have studied the effects of CD39 gene deletion on NK cells in dictating outcomes after partial hepatic ischemia/reperfusion injury (IRI). We show in mice that gene deletion of CD39 is associated with marked decreases in phosphohydrolysis of adenosine triphosphate (ATP) and adenosine diphosphate to adenosine monophosphate on NK cells, thereby modulating the type-2 purinergic (P2) receptors demonstrated on these cells. We note that CD39-null mice are protected from acute vascular injury after single-lobe warm IRI, and, relative to control wild-type mice, display significantly less elevation of aminotransferases with less pronounced histopathological changes associated with IRI. Selective adoptive transfers of immune cells into Rag2/common gamma null mice (deficient in T cells, B cells, and NK/NKT cells) suggest that it is CD39 deletion on NK cells that provides end-organ protection, which is comparable to that seen in the absence of interferon gamma. Indeed, NK effector mechanisms such as interferon gamma secretion are inhibited by P2 receptor activation in vitro. Specifically, ATPgammaS (a nonhydrolyzable ATP analog) inhibits secretion of interferon gamma by NK cells in response to interleukin-12 and interleukin-18, providing a mechanistic link between CD39 deletion and altered cytokine secretion. CONCLUSION: We propose that CD39 deficiency and changes in P2 receptor activation abrogate secretion of interferon gamma by NK cells in response to inflammatory mediators, thereby limiting tissue damage mediated by these innate immune cells during IRI.
  Hepatology 12/2009; 51(5):1702-11. · 11.66 Impact Factor
• Article: A novel view for visualizing a left pulmonary artery thromboembolus with intraoperative transesophageal echocardiography.

  Martina Nowak, Stanton K Shernan, Holger K Eltzschig, Peter Rosenberger
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  ABSTRACT: Visualization of thromboembolic material in the pulmonary artery is often difficult on transesophageal echocardiography, especially in the left pulmonary artery, because of the position of the left main bronchus. We present a case in which thromboembolic material within the midleft pulmonary artery was incidentally diagnosed using additional, modified transesophageal echocardiography views, in a patient undergoing mitral valve repair.
  Journal of Clinical Anesthesia 04/2008; 20(2):136-8. · 1.21 Impact Factor
• Source

  Available from: ucdenver.edu

  Article: The influence of epiaortic ultrasonography on intraoperative surgical management in 6051 cardiac surgical patients.

  Peter Rosenberger, Stanton K Shernan, Michaela Löffler, Prem S Shekar, John A Fox, Jayshree K Tuli, Martina Nowak, Holger K Eltzschig
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  ABSTRACT: Intraoperative echocardiography has become a mainstay monitor of cardiac function and a popular diagnostic tool in patients undergoing cardiac procedures. Previous reports suggest that epiaortic ultrasonography (EU) is superior to transesophageal echocardiography and manual palpation in identifying ascending aortic atheroma. Its impact on surgical decision making has not been thoroughly investigated, however. We retrospectively analyzed the medical records of 6051 consecutive patients who underwent EU of their ascending aorta during cardiac operations between 1996 and 2006 to determine a potential impact on intraoperative surgical decision making. Aortic atheroma was graded according to standard classification. Neurologic complications were evaluated according to the Society of Thoracic Surgeon definition for stroke and transient ischemic attack (TIA). The overall impact of EU on surgical decision making was 4.1% and included a change in the technique for inducing cardiac arrest in 1.8%, aortic atherectomy or replacement surgery in 0.8%, requirement for off-pump coronary artery bypass grafting (CABG) in 0.6%, avoidance of aortic cross-clamping and use of ventricular fibrillatory arrest in 0.5%, change in arterial cannulation site in 0.2%, or avoidance of aortic cannulation in 0.2%. The greatest affect of EU was observed in patients undergoing combined CABG with aortic/mitral valve procedures (6.7%). The smallest impact was seen in patients undergoing mitral valve operations (1.4%). Aortic atheroma was more frequent on the anterior aspect of the aorta (n = 171) in patients with a change in surgical plan than on the posterior aspect (n = 78). The overall stroke rate was lower in patients with intraoperative EU compared with all patients undergoing surgical procedures. Epiaortic ultrasonography is a useful technique to detect ascending aortic atheroma, has a significant impact on surgical decision making in more than 4% of cardiac surgical patients, and might result in improved perioperative neurologic outcome.
  The Annals of thoracic surgery 03/2008; 85(2):548-53. · 3.74 Impact Factor
• Article: Right ventricular dissection diagnosed on transesophageal echocardiography.

  Jörn Karhausen, Martina Nowak, Gregory S Couper, Vladimir Formanek, Valbona Mirakaj, Andrew Locke, Stanton K Shernan, Peter Rosenberger
  Anesthesia and analgesia 03/2008; 106(2):412-4. · 3.08 Impact Factor
• Article: Predictive index for renal replacement therapy.

  Peter Rosenberger, Martina Nowak, Stanton K Shernan
  JAMA The Journal of the American Medical Association 09/2007; 298(7):737; author reply 737-8. · 30.03 Impact Factor
• Article: Critical role of intraoperative transesophageal echocardiography for detection of extrapulmonary thromboemboli during surgical pulmonary embolectomy.

  Martina Nowak, Holger K Eltzschig, Prem Shekar, Stanton K Shernan, Peter Rosenberger
  Anesthesiology 07/2006; 104(6):1346; author reply 1346-7. · 5.36 Impact Factor