An Experimental Study of Transvenous Defibrillation Using a Coronary Sinus Catheter

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71902/1/j.1540-8167.1989.tb01561.x.pd

Regulatory activity revealed by dynamic correlations in gene expression noise

Gene regulatory interactions are context dependent, active in some cellular states but not in others. Stochastic fluctuations, or 'noise', in gene expression propagate through active, but not inactive, regulatory links^(1,2). Thus, correlations in gene expression noise could provide a noninvasive means to probe the activity states of regulatory links. However, global, 'extrinsic', noise sources generate correlations even without direct regulatory links. Here we show that single-cell time-lapse microscopy, by revealing time lags due to regulation, can discriminate between active regulatory connections and extrinsic noise. We demonstrate this principle mathematically, using stochastic modeling, and experimentally, using simple synthetic gene circuits. We then use this approach to analyze dynamic noise correlations in the galactose metabolism genes of Escherichia coli. We find that the CRP-GalS-GalE feed-forward loop is inactive in standard conditions but can become active in a GalR mutant. These results show how noise can help analyze the context dependence of regulatory interactions in endogenous gene circuits

Friction effects on collective mechanisms of short term memory

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004.Includes bibliographical references (p. 61).Short term memory is often correlated with persistent changes in neuronal firing rates in response to transient inputs. This thesis models the persistent maintenance of an analog eye position signal by an oculomotor neural integrator receiving transient eye movement commands. We show analytically how using neurons with multiple bistable dendritic compartments can enhance the robustness of eye fixations to mistuning while reproducing the observed linear relationship between neuronal firing rates and eye position. We calculate the network dynamics and tolerance to mistuning. Finally, we demonstrate that dendritic bistability can improve robustness in a biophysically realistic network of conductance based neurons.by Joseph H. Levine.M.Eng

Reversal of dysfunction in postischemic stunned myocardium by epinephrine and postextrasystolic potentiation

After brief coronary occlusions, myocardium may become "stunned," exhibiting prolonged depression of function despite the absence of necrosis. Because of the accompanying decline in adenosine triphosphate and adenine nucleotide precursors, a deficiency of energy supply has been proposed as the basis for postischemic dysfunction. This study examined whether sufficient functional and metabolic reserve exists in stunned myocardium to sustain a prolonged, maximal inotropic response to epinephrine and postextrasystolic potentiation. In 11 open chest dogs, the left anterior descending coronary artery was occluded for 5 minutes, followed by 10 minutes of reflow, repeated 12 times, with a final 1 hour recovery period. Regional myocardial function was measured using pairs of ultrasonic dimension crystals implanted in ischemic and nonischemic zones.During repetitive reflows a progressive decrease in mean systolic segment shortening occurred: baseline 21.8%, 1st reflow 15.2%, 12th reflow 4.3%, 1 hour recovery 7.9%. Intravenous epinephrine, titrated to produce a maximal inotropic response, caused segment shortening to increase to 21.6% after 10 minutes and to 24.8 % after 1 hour of infusion, despite a 20 mm Hg increase in systolic pressure. The same dose of epinephrine given before ischemia increased segment shortening to 30.5%. In six of the dogs, postextrasystolic potentiation before ischemia increased segment shortening from 21.8 to 31.1%, and after 1 hour of recovery from ischemia, from 7.9 to 24.8%. Lesser increases in segment shortening were also seen in nonischemic segments.The results indicate that stunned myocardium possesses considerable functional reserve. Deficient energy stores are therefore not likely to be the basis for depressed function seen at rest in stunned myocardium

Project LOBSTAQ : investigations on lobster (Homarus americanus) aquaculture, ecology and tertiary sewage treatment in controlled environmental systems

Research was based on different aspects of incorporating Homarus Americanus cultural into the multi-trophic level marine aquaculture-wastewater treatment system of the Environmental Systems laboratory at Woods Hole. Experiments were directed .toward optimizing food sources available within the system, developing designs to facilitate high density lobster growth, and elucidating the ecology of Homarus. The aquaculture-wastewater treatment system uses secondary sewage effluent or its equivalent as a nutrient source for marine phytoplankton ponds which in turn are fed into raceways containing racks of bivalves. The bivalves produce soluble nutrients used to raise macroalgae, and solid material (biodeposits) used to raise various deposit feeders. Almost all the N and over 50% of the P is removed from the wastewater by the artificial food chain.Prepared under NSF Grant GY-1154

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT