Identification of General and Heart-Specific miRNAs in Sheep (Ovis aries).

MicroRNAs (miRNAs or miRs) are small regulatory RNAs crucial for modulation of signaling pathways in multiple organs. While the link between miRNAs and heart disease has grown more readily apparent over the past three years, these data are primarily limited to small animal models or cell-based systems. Here, we performed a high-throughput RNA sequencing (RNAseq) analysis of left ventricle and other tissue from a pre-clinical ovine model. We identified 172 novel miRNA precursors encoding a total of 264 mature miRNAs. Notably, 84 precursors were detected in both the left ventricle and other tissues. However, 10 precursors, encoding 11 mature sequences, were specific to the left ventricle. Moreover, the total 168 novel miRNA precursors included 22 non-conserved ovine-specific sequences. Our data identify and characterize novel miRNAs in the left ventricle of sheep, providing fundamental new information for our understanding of protein regulation in heart and other tissues.

Method of isolated ex vivo lung perfusion in a rat model: lessons learned from developing a rat EVLP program.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and "pearls of wisdom"/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Multidimensional sternal fixation to overcome a "floating" sternum.

This case report describes the repair of a complete sternal dehiscence of the lower right sternum using sternal wires, manubrial plates, and a Talon closure device for rigid, multidimensional sternal fixation. Sternal dehiscence is a rare but significant cause of morbidity for patients undergoing median sternotomy. The risk factors for this complication are well described and although sternal wires have traditionally been used for primary closure, rigid fixation with sternal plates is a viable alternative to avoid dehiscence in this high-risk cohort.

A nonthoracotomy myocardial infarction model in an ovine using autologous platelets.

OBJECTIVE: There is a paucity of a biological large animal model of myocardial infarction (MI). We hypothesized that, using autologous-aggregated platelets, we could create an ovine model that was reproducible and more closely mimicked the pathophysiology of MI. METHODS: Mepacrine stained autologous platelets from male sheep (n = 7) were used to create a myocardial infarction via catheter injection into the mid-left anterior descending (LAD) coronary artery. Serial daily serum troponin measurements were taken and tissue harvested on post-embolization day three. Immunofluorescence microscopy was used to detect the mepacrine-stained platelet-induced thrombus, and histology performed to identify three distinct myocardial (infarct, peri-ischemic "border zone," and remote) zones. RESULTS: Serial serum troponin levels (µg/mL) measured 0.0 ± 0.0 at baseline and peaked at 297.4 ± 58.0 on post-embolization day 1, followed by 153.0 ± 38.8 on day 2 and 76.7 ± 19.8 on day 3. Staining confirmed distinct myocardial regions of inflammation and fibrosis as well as mepacrine-stained platelets as the cause of intravascular thrombosis. CONCLUSION: We report a reproducible, unique model of a biological myocardial infarction in a large animal model. This technique can be used to study acute, regional myocardial changes following a thrombotic injury.

Jugular venous oxygenation during hypothermic cardiopulmonary bypass in patients at risk for abnormal cerebral autoregulation: influence of alpha-Stat versus pH-stat blood gas management.

In a prospective, randomized study of cardiac surgical patients at risk for impaired cerebral blood flow autoregulation, we compared alpha-stat and pH-stat blood gas management. The 40 patients enrolled had age >70 yr, diabetes, prior stroke, or uncontrolled hypertension. During hypothermia and early rewarming, jugular oxygen tensions were significantly lower in alpha-stat patients (n = 12) than pH-stat patients (n = 19; P < 0.05). During rewarming, jugular venous desaturation (i.e., SjvO(2) <50%) occurred in 6 of 12 alpha-stat patients, but no pH-stat patients (P = 0.0006). Patients at risk for poor cerebral autoregulation have higher oxygen tensions and saturations if pH-stat blood gas management is used during cardiopulmonary bypass.

Temperature during cardiopulmonary bypass: the discrepancies between monitored sites.

We performed studies in patients to determine whether temperature recordings from sites commonly monitored during hypothermic cardiopulmonary bypass adequately reflect cerebral temperature. In Study I (n = 12), temperatures monitored in the jugular bulb (JB) were compared with those recorded in the nasopharynx, esophagus, bladder, and rectum. In Study II (n = 30), temperature was also monitored in the arterial outlet of the membrane oxygenator. A calibrated recorder continuously and simultaneously recorded all temperatures. Study I found large temperature discrepancies between the JB and all other body sites during cooling and rewarming. There was considerable interindividual variability in the degree of discrepancy between the JB and other sites. Study II produced similar results but also showed that JB temperature reached equilibration with the temperature of blood entering the patient via the arterial outlet of the membrane oxygenator after cooling for 3.3 +/- 1.3 min and after rewarming for 16.5 +/- 5.5 min. Analysis of variance revealed that this arterial outlet site had the smallest average discrepancy of all temperature sites relative to the JB site (P < 0.001). In summary, temperatures measured in body sites over-estimated JB temperature during cooling and under-estimated it during rewarming, whereas arterial outlet blood temperature provided a good approximation.