Comparison of Isoflurane and α-Chloralose in an Anesthetized Swine Model of Acute Pulmonary Embolism Producing Right Ventricular Dysfunction

Pulmonary embolism (PE) is a leading cause of sudden cardiac death, and a model is needed for testing potential treatments. In developing a model, we compared the hemodynamic effects of isoflurane and α-chloralose in an acute swine model of PE because the choice of anesthesia will likely affect the cardiovascular responses of an animal to PE. At baseline, swine that received α-chloralose (n = 6) had a lower heart rate and cardiac output and higher SpO_2, end-tidal CO_2, and mean arterial pressure than did those given isoflurane (n = 9). After PE induction, swine given α-chloralose compared with isoflurane exhibited a lower heart rate (63 ± 10 compared with 116 ± 15 bpm) and peripheral arterial pressure (52 ± 12 compared with 61 ± 12 mm Hg); higher SpO₂ (98% ± 3% compared with 95% ± 1%), end-tidal CO₂ (35 ± 4 compared with 32 ± 5), and systolic blood pressure (121 ± 8 compared with 104 ± 20 mm Hg); and equivalent right ventricular:left ventricular ratios (1.32 ± 0.50 compared with 1.23 ± 0.19) and troponin I mean values (0.09 ± 0.07 ng/mL compared with 0.09 ± 0.06 ng/mL). Isoflurane was associated with widely variable fibrinogen and activated partial thromboplastin time. Intraexperiment mortality was 0 of 6 animals for α-chloralose and 2 of 9 swine for isoflurane. All swine anesthetized with α-chloralose survived with sustained pulmonary hypertension, RV-dilation-associated cardiac injury without the confounding vasodilatory or coagulatory effects of isoflurane. These data demonstrate the physiologic advantages of α-chloralose over isoflurane for anesthesia in a swine model of severe submassive PE.Abbreviations: LV, left ventricle; PAP, pulmonary arterial pressure; PE, pulmonary embolism; RV, right ventriclePulmonary embolism (PE) is one of the leading causes of noncardiac sudden death in Western nations and is the third most common cause of cardiovascular morbidity.^4,6,7,18 In survivors, severe PE damages the right heart, leading to a clinical course complicated by hypotension and circulatory shock, suggesting acute right heart failure in about 10% of patients and followed by persistent pulmonary hypertension or right ventricular dysfunction and dyspnea in at least 15% of patients.^{9,15,16,23,29} To test treatments to reduce right heart failure, a standardized model that is repeatable, accurate, and precise and that mimics the gross pathologic, cardiovascular, pulmonary, autonomic, hematologic, biochemical, and cellular characteristics of PE in humans with disease is needed.⁸Three lines of rationale favor domestic pigs as a model for PE. Several publications, using different methods of anesthesia, have found that swine manifest hemodynamic responses similar to those of humans in the presence of autologous PE, including elevated heart rate, decreased cardiac output, and reduced oxygen saturation.^2,12,30 Swine have similar platelet concentrations, and their coagulation profile on thromboelastography has been shown to be similar to humans, with the exception of higher fibrin crosslinking but less fibrin, leading to resistance to plasmin.^5,11,19,34 Market swine, which would otherwise be destined for slaughter, are relatively cost effective compared with other large animals and are of sufficient size for placement of an adult pulmonary arterial catheter for measurement of pulmonary vascular resistance in a closed-chest preparation.In view of the differences in the hemodynamic effects of different anesthetic agents, the choice of anesthesia will likely affect the cardiovascular responses of an animal to PE. However, current literature lacks a methodologic publication that compares the cardiovascular, right ventricular, pulmonary, and hematologic responses to PE in closed-chest swine models incorporating different anesthetic regimens.Figure 1 presents features of an ideal animal model for the purpose of testing treatments for PE. To develop a swine model of PE that closely resembles this physiologic ideal model, we induced PE in swine maintained in a surgical plane of anesthesia with either isoflurane or α-chloralose. Each of these agents has potential advantages and disadvantages. Isoflurane can be titrated minute by minute but causes undesirable vasodilation, whereas α-chloralose is believed to preserve cardiovascular reflexes but requires heating to dissolve and continuous infusion or repeated boluses.^26,35 We hypothesized that, compared with isoflurane, α-chloralose would meet more of the features described in Figure 1.Open in a separate windowFigure 1.Desirable features of large animal model of severe submassive PE designed for translational research.     

Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction

Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process.     

Protein changes in macrophages induced by plasma from rats exposed to 35 GHz millimeter waves

A macrophage assay and proteomic screening were used to investigate the biological activity of soluble factors in the plasma of millimeter wave‐exposed rats. NR8383 rat macrophages were incubated for 24 h with 10% plasma from male Sprague–Dawley rats that had been exposed to sham conditions, or exposed to 42 °C environmental heat or 35 GHz millimeter waves at 75 mW/cm² until core temperature reached 41.0 °C. Two‐dimensional polyacrylamide gel electrophoresis, image analysis, and Western blotting were used to analyze approximately 600 protein spots in the cell lysates for changes in protein abundance and levels of 3‐nitrotyrosine, a marker of macrophage stimulation. Proteins of interest were identified using peptide mass fingerprinting. Compared to plasma from sham‐exposed rats, plasma from environmental heat‐ or millimeter wave‐exposed rats increased the expression of 11 proteins, and levels of 3‐nitrotyrosine in seven proteins, in the NR8383 cells. These altered proteins are associated with inflammation, oxidative stress, and energy metabolism. Findings of this study indicate both environmental heat and 35 GHz millimeter wave exposure elicit the release of macrophage‐activating mediators into the plasma of rats. Bioelectromagnetics 31:656–663, 2010. © 2010 Wiley‐Liss, Inc.     

Very-Long-Chain Fatty Acids Are Involved in Polar Auxin Transport and Developmental Patterning in Arabidopsis

Very-long-chain fatty acids (VLCFAs) are essential for many aspects of plant development and necessary for the synthesis of seed storage triacylglycerols, epicuticular waxes, and sphingolipids. Identification of the acetyl-CoA carboxylase PASTICCINO3 and the 3-hydroxy acyl-CoA dehydratase PASTICCINO2 revealed that VLCFAs are important for cell proliferation and tissue patterning. Here, we show that the immunophilin PASTICCINO1 (PAS1) is also required for VLCFA synthesis. Impairment of PAS1 function results in reduction of VLCFA levels that particularly affects the composition of sphingolipids, known to be important for cell polarity in animals. Moreover, PAS1 associates with several enzymes of the VLCFA elongase complex in the endoplasmic reticulum. The pas1 mutants are deficient in lateral root formation and are characterized by an abnormal patterning of the embryo apex, which leads to defective cotyledon organogenesis. Our data indicate that in both tissues, defective organogenesis is associated with the mistargeting of the auxin efflux carrier PIN FORMED1 in specific cells, resulting in local alteration of polar auxin distribution. Furthermore, we show that exogenous VLCFAs rescue lateral root organogenesis and polar auxin distribution, indicating their direct involvement in these processes. Based on these data, we propose that PAS1 acts as a molecular scaffold for the fatty acid elongase complex in the endoplasmic reticulum and that the resulting VLCFAs are required for polar auxin transport and tissue patterning during plant development.     

An alternative to fish oils: Metabolic engineering of oil-seed crops to produce omega-3 long chain polyunsaturated fatty acids

It is now accepted that omega-3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA; 20:5Δ5,8,11,14,17) and docosahexaenoic acid (DHA, 22:6Δ4,7,10,13,16,19) play important roles in a number of aspects of human health, with marine fish rich in these beneficial fatty acids our primary dietary source. However, over-fishing and concerns about pollution of the marine environment indicate a need to develop alternative, sustainable sources of very long chain polyunsaturated fatty acids (VLC-PUFAs) such as EPA and DHA. A number of different strategies have been considered, with one of the most promising being transgenic plants “reverse-engineered” to produce these so-called fish oils. Considerable progress has been made towards this goal and in this review we will outline the recent achievements in demonstrating the production of omega-3 VLC-PUFAs in transgenic plants. We will also consider how these enriched oils will allow the development of nutritionally-enhanced food products, suitable either for direct human ingestion or for use as an animal feedstuff. In particular, the requirements of aquaculture for omega-3 VLC-PUFAs will act as a strong driver for the development of such products. In addition, biotechnological research on the synthesis of VLC-PUFAs has provided new insights into the complexities of acyl-channelling and triacylglycerol biosynthesis in higher plants.     

2-Aryl benzimidazoles featuring alkyl-linked pendant alcohols and amines as inhibitors of checkpoint kinase Chk2

A series of benzimidazole compounds containing pendant alcohol and amine moieties was found to be active against checkpoint kinase Chk2. These compounds were prepared to examine a potential hydrogen bond interaction with an active site residue and to investigate replacement of a biaryl linker with an aliphatic system in an effort to improve solubility.     

Rational metabolic engineering of transgenic plants for biosynthesis of omega-3 polyunsaturates

The health-beneficial effects of long-chain polyunsaturated fatty acids (LC-PUFAs), derived mainly from fish oil, coupled with the growing requirement for an alternative and sustainable source of these compounds, has led to efforts to engineer oilseed crops for their production. LC-PUFA synthesis has been achieved using combinations of heterologous endomembrane desaturases and elongases expressed in model oilseed plants. Two general approaches have been employed that both use endogenous 18 carbon fatty acids as the starting substrates: the Delta6- and Delta8-pathways, which perform desaturation followed by elongation or elongation followed by desaturation, respectively. However, yields above 20% have not yet been realized owing to bottlenecks that become apparent in the endogenous biosynthetic pathways when heterologous genes are expressed. These bottlenecks might be caused partly by inefficient non-native enzymes in the host system or also by suboptimal acyl-exchange mechanisms between the acyl-CoA and lipid class pools. The fine-tuning of the fatty acid flux between the acyl-CoA, phospholipid, and triacylglycerol pools will be essential to maximise polyunsaturated fatty acid yields in seed oils. In addition, efficient substrate channelling and lipid synthesis could depend on specific endoplasmic reticulum subdomain localisation for key endogenous enzymes, and this organization could be compromised in heterologous systems.