Electrodynamics of Media

Contains research objectives and reports on four research projects.Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E

Cardioprotective effects of amlodipine in the ischemic-repefused heart

Amlodipine is a a dihydropyridine derivative belonging to the group of pharmacologic calcium entry blocking agents and is characterized as having a slow onset and relatively long duration of action with minimal effects on cardiac electrophysiology and myocardial contractility.The protective effect of amlodipine was studied in isolated blood-perfused feline hearts made globally ischemic for 60 minutes followed by reperfusion for 60 minutes. Ischemic-lnduced alterations of left ventricular developed pressure and compliance were monitored. In 11 control and 7 drug-treated hearts, amloipine produced significant decreases in myocardial oxygen consumption (6.2 +/- 0.4 to 4.4 +/- 0.4 ml oxygen/min/100 g) and coronary vascular resistance, as assessed by changes in perfusion pressure (120 +/- 1 to 100 +/- 4 mm Hg). Amlodipine administered before the onset of global ischemia decreased the development of ischemic contracture as reflected by a progressive increase in resting left ventricular diastolic pressure. The return of contractile function, 60 minutes after reperfusion, improved significantly in the amlodipine-treated group compared with controls, and there was better maintenance of the tissue concentration of Na+, Ca2+ and K+.A canine model of regional myocardial ischemia (90 minutes) followed by 6 hours of reperfusion was used to assess the cardioprotective effects of amlodyrine, 150 [mu]g/kg, administered 15 minutes before reperfusion. Infarct size, expressed as a percentage of the area at risk, was smaller in the amlodipine-treated group (n = 10) than in the control group (n = 10) (34.5 +/- 3.8% vs 45.9 +/- 2.8%, P = 0.027). Risk region size did not differ between groups and both groups were comparable with respect to the hemodynamic parameters of heart rate, blood pressure and rate-pressure product. Amlodipine prevented the gradual reduction in coronary blood flow observed in the control group.It is concluded that amlodipine reduces myocardial ischemic injury by mechanism(s) that may involve a reduction in myocardial oxygen demand as well as by positively influencing transmembrane Ca2+ fluxes during ischemia and reperfusion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27687/1/0000071.pd

Cardioprotective effects of amlodipine on ischemia and reperfusion in two experimental models

The cardioprotective effect of amlodipine, a longacting dihydropyridine derivative, was studied in 2 experimental models of ischemia and reperfusion.Isolated and blood-perfused feline hearts were made globally ischemic for 60 minutes and then reperfused for 60 minutes. Alterations of left ventricular developed pressure and compliance were monitored in both amlodipine-treated hearts and salinetreated control animals. Changes in perfusion pressure indicated that amlodipine significantly reduced myocardial oxygen consumption and coronary vascular resistance. Furthermore, a progressive increase in resting left ventricular diastolic pressure indicated that amlodipine, administered before the onset of global ischemia, attenuated the development of ischemic contracture. Return of contractile function 60 minutes after reperfusion and maintenance of tissue concentrations of electrolytes were significantly better in the amlodipinetreated group than in the control animals.In intact canine hearts, regional myocardial ischemia was induced for 90 minutes, followed by 6 hours of reperfusion. Although the hemodynamic variables and the size of the region of risk did not differ significantly between treated animals and control animals, the infarct size was significantly smaller in the amlodipine-treated group than in the control animals, and a gradual reduction in coronary blood flow was observed in the control group that was prevented in the amlodipine group. A comparison of these findings with those observed with oxygen radical scavengers also is discussed.A detailed report of these studies was published in The American Journal of Cardiology (1989;64:101I-116I). This review is included here to maintain continuity of the symposium for the convenience of the reader.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28306/1/0000060.pd

Развитие экстремального туризма в Крыму

Целью данной работы является на основе географического анализа факторов становления и особенностей развития экстремального туризма в Крыму разработать рекомендации по усовершенствованию данной отрасли туристской деятельности для создания привлекательного образа Крыма на международной арене

Does drug‐induced sleep endoscopy predict surgical success in transoral robotic multilevel surgery in obstructive sleep apnea?

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136419/1/lary26255_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136419/2/lary26255.pd

Reduction in digitalis-associated postinfarction mortality with nadolol in conscious dogs

Previously, we have demonstrated an increased incidence of lethal ischemic arrhythmias in postinfarction dogs with clinically observable serum digoxin concentrations, and a significant reduction in digitalis-related lethal ischemic arrhythmias after subacute left stellectomy. In the present study, the protective actions of acute beta-adrenoceptor blockade with nadolol, 1.0 mg/kg administered intravenously immediately preceding the induction of posterolateral myocardial ischemia, were assessed in conscious dogs with recent, small anterior myocardial infarctions pretreated with digoxin, 0.0125 mg/kg/day intravenously, for 5 to 7 consecutive days (total N = 11). A cohort of postinfarction dogs pretreated with digoxin alone served as a control group (total N = 26). Pre vs postdigoxin electrophysiologic testing indicated reductions in myocardial refractoriness in ventricular noninfarct and infarct in both treatment groups, whereas the administration of nadolol tended to reverse the reductions in ventricular refractoriness. Arrhythmia-related deaths in response to posterolateral myocardial ischemia were reduced from 12 of 20 (60%) in the digoxin control group to 2 of 10 (20%) in the digoxin + nadolol group (p = 0.039). Serum digoxin concentrations (1.29 +/- 0.14 ng/ml vs 1.39 +/- 0.24 ng/ml), underlying anterior myocardial infarct size (6.9 +/- 1.5% vs 4.6 +/- 0.9% of left ventricle), and developing posterolateral myocardial infarct size (22.8 +/- 2.5% vs 17.5 +/- 3.6% of left ventricle) did not differ significantly between the digoxin and digoxin + nadolol groups. Acute beta-adrenoceptor blockade with nadolol appears to reduce digitalis-mediated ischemic postinfarction mortality, possibly because of a salutary increase in ventricular refractoriness.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27463/1/0000504.pd

Evaluation of Simulator Cueing Fidelity for Rotorcraft Certification by Simulation

Before their entry into service, newly developed rotorcraft must go through an extensive certification process in order to receive a type certificate from the certification authority. A vital and long-lasting phase of this process is the compliance demonstration. This phase involves a large amount of flight testing, which leads to high expenses for the rotorcraft manufacturer and can be considered as high-risk when it comes to rotorcraft safety, especially for scenarios including control system or engine failures, as in the case of a category-A rejected take-off (CAT-A RTO). The Rotorcraft Certification by Simulation (RoCS) CleanSky2 research project aims to reduce the amount of flight testing required for compliance demonstration by using flight simulation, to achieve an increase in safety (less hazardous situations) and effectiveness, and a reduction in certification duration and costs. Within the project, pilot-in-the-loop simulator test campaigns were conducted at DLR and NLR, investigating the visual cueing fidelity required for performing a CAT-A RTO scenario. Emphasis was put on varying the available field of view (FoV) for the pilot and investigating the suitability of virtual reality (VR) devices. Subjective and objective results from these simulator campaigns, as well as pilot comments are presented in this paper

Streptokinase improves reperfusion blood flow after coronary artery occlusion

Streptokinase is an effective thrombolytic agent which, with early restoration of coronary blood flow, has the potential for limiting infarct size. Distinct from thrombolysis, we studied the effects of streptokinase on reperfusion coronary blood flow and infarct size. Open-chest anesthetized canines underwent a 90 minute snare occlusion of the left circumflex coronary artery followed by release and reperfusion through a critical stenosis for 6 hours. The animals were assigned randomly to two groups. Intracoronary streptokinase [group 1 (n = 8): 6000 IU/kg in 3 ml of saline] or saline [group 2 (n = 8): 3 ml of saline] was infused at 0.05 ml/min for 60 minutes beginning 30 minutes before reperfusion. Coronary blood flow was stable in group 1 during reperfusion, while in group 2 it fell during 6 hours of reperfusion (30 +/- 4 ml/min to 18 +/- 2 ml/min, P = 0.05). The ST-segment elevation on the limb lead II electrocardiogram 15 minutes after coronary artery occlusion was similar in both groups (group 1: 3.9 +/- 0.6 mV, group 2: 2.3 +/- 0.5 mV), suggesting the extent of myocardial ischemia was also similar in both groups. The infarct sizes were similar when expressed both as a percent of the total left ventricular mass [(IZ/LV) group 1: 17 +/- 2.5%, group 2: 17.5 +/- 2.5%] or as a percent of the area at risk of infarction [(IZ/AR) group 1: 39 +/- 6%, group 2: 39 +/- 5%]. In both groups, the mass of left ventricle dependent on the blood flow distribution of the left circumflex coronary artery was similar when compared to total left ventricular mass [(AR/LV) group 1: 41 +/- 3%, group 2: 44 +/- 4%]. These results demonstrate that streptokinase maintains reperfusion coronary blood flow through a critical stenosis at a rate similar to baseline levels. Despite the fact that coronary blood flow remained stable with streptokinase during reperfusion, infarct size was not limited after 90 minutes of fixed coronary artery occlusion in this canine model of myocardial injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27920/1/0000344.pd

Neoplastic transformation of breast epithelial cells by genotoxic stress

<p>Abstract</p> <p>Background</p> <p>Exposure to genotoxic stresses such as radiation and tobacco smoke can cause increased cancer incidence rate as reflected in an in depth meta-analysis of data for women and breast cancer incidence. Published reports have indicated that exposures to low dose radiation and tobacco smoke are factors that contribute to the development of breast cancer. However, there is a scarcity of information on the combinatorial effects of low dose radiation and tobacco smoke on formation and progression of breast cancer. The combination of these two genotoxic insults can induce significant damage to the genetic material of the cells resulting in neoplastic transformation.</p> <p>Methods</p> <p>To study the effects of low dose ionizing radiation and tobacco smoke on breast cells, MCF 10A cells were treated either with radiation (Rad - 0.1 Gray) or cigarette smoke condensate (Csc - 10 microgram/ml of medium) or a combination of Rad + Csc. Following treatments, cells were analyzed for cell cycle distribution patterns and the ability to extrude the Hoechst 33342 dye. In addition, <it>in vitro </it>invasion and migration as well as mammosphere formation assays were performed. Finally, differential gene expression profiles were generated from the individual and combination treatment.</p> <p>Results</p> <p>Exposure of MCF 10A cells to the combination of radiation plus cigarette smoke condensate generated a neoplastic phenotype. The transformed phenotype promoted increased mammosphere numbers, altered cell cycle phases with a doubling of the population in S phase, and increased invasion and motility. Also, exclusion of Hoechst 33342 dye, a surrogate marker for increased ABC transporters, was observed, which indicates a possible increase in drug resistance. In addition, changes in gene expression include the up regulation of genes encoding proteins involved in metabolic pathways and inflammation.</p> <p>Conclusions</p> <p>The results indicate that when normal breast cells are exposed to low dose radiation in combination with cigarette smoke condensate a phenotype is generated that exhibits traits indicative of neoplastic transformation. More importantly, this is the first study to provide a new insight into a possible etiology for breast cancer formation in individuals exposed to low dose radiation and tobacco smoke.</p

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation