Ups and Downs in UN History

A peaceful world order was for centuries a noble, yet unattainable ideal, until President Woodrow Wilson called for action in the last year of the First World War. Sickened by four years of slaughter on the battlefields of Europe, the victors wrote a Covenant of the League of Nations into the Treaty of Versailles. It was the kiss of death. The Treaty was a nineteenth century peace—vengeful, greedy, and fearridden, which registered only the absence of any ethical and political architecture for a new era. The Senate and the people of the United States promptly rejected both the Treaty and the League. Without America’s presence, the grand experiment stumbled down the scale into a melancholy farce. In 1941, under President Franklin D. Roosevelt, the United States took the initiative again, molding the wartime alliance of “united nations” into the world organization of that name. From the beginning, the United Nations (UN) reflected high hopes and stormy times, sometimes in a carnival mirror of weird distortion. Most importantly, at first and still, it showed that the United States was engaged in the international scene

Visualizing the dynamics of HIV-specific cytotoxic T-cells in extracellular matrix

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2012.CD-ROM contains copy of thesis in .pdf format and files in .mov format.Cataloged from PDF version of thesis.Includes bibliographical references (p. 76-84).Cytotoxic lymphocytes (CTLs) traffic through tissues in search of antigen and mount protective immune responses against viral infections and cancer. While molecular mechanisms of CTL antiviral effector functions have been established in vitro, they have been defined in the absence of physiological dynamics and migration. Furthermore, longterm dynamics of single cells have been inaccessible in vivo, where brief imaging durations have been achieved (-30-60 min). Presently, several key aspects of CTL dynamics and function remain unknown: whether individual CTLs migrating within tissues kill multiple targets, if CTLs exhibit spatiotemporal coordination of effector functions, or if migrating CTLs effect these functions in different compartments. Thus, a mechanistic understanding of multidimensional CTL function might directly inform therapeutic strategies. In this thesis, we first developed an approach for long-term high-speed optical imaging of cellular dynamics for continuous periods of 24 hours. HIV-specific CTLs were visualized as they encountered CD4+ target cells within a three-dimensional extracellular matrix tissue model supporting migration of both CTLs and targets. Using this approach, we found that high-avidity CTLs engaged, arrested, and killed the first target encountered with near-perfect efficiency. These CTLs remained in contact with dead targets for hours, accumulating TCR signals and upregulating antiviral cytokine and chemokine secretion for >12 hours, but were refractory to killing additional targets. By contrast, lower-avidity CTLs exhibited poor efficiency and target migration directly impeded CTL killing. Thus, high-avidity CTLs coordinate multiple antiviral functions in four dimensions (3D space and time): effectively destroying the first detected infected cell during an initial "commitment phase", but rapidly transitioning to a prolonged "secretory phase." In vivo, coordination of lytic and non-lytic effector functions will direct the local inflammatory milieu and recruit additional effectors to the tissue. We conclude that the efficiency of antigen recognition by individual migrating CTLs is a critical, but previously undefined, parameter of CTL function. Furthermore, TCR avidity and initial CTL efficiency are prerequisites for sustained antiviral polyfunctionality; together these parameters define a highly effective, multidimensional CTL response, which may inform the design of increasingly effective vaccines.by Maria Hottelet Foley.Ph.D

High Avidity CD8+ T Cells Efficiently Eliminate Motile HIV-Infected Targets and Execute a Locally Focused Program of Anti-Viral Function

The dissemination of HIV from an initial site of infection is facilitated by motile HIV-infected CD4+ T-cells. However, the impact of infected target cell migration on antigen recognition by HIV-specific CD8+ T-cells is unclear. Using a 3D in vitro model of tissue, we visualized dynamic interactions between HIV-infected or peptide-pulsed CD4+ T-cells and HIV-specific CD8+ T-cells. CTLs engaged motile HIV-infected targets, but ∼50% of targets broke contact and escaped. In contrast, immobilized target cells were readily killed, indicating target motility directly inhibits CD8+ T-cell function. Strong calcium signals occurred in CTLs killing a motile target but calcium signaling was weak or absent in CTLs which permitted target escape. Neutralization of adhesion receptors LFA-1 and CD58 inhibited CD8+ T-cell function within the 3D matrix, demonstrating that efficient motile target lysis as dependent on adhesive engagement of targets. Antigen sensitivity (a convolution of antigen density, TCR avidity and CD8 coreceptor binding) is also critical for target recognition. We modulated this parameter (known as functional avidity but referred to here as “avidity” for the sake of simplicity) by exploiting common HIV escape mutations and measured their impact on CTL function at the single-cell level. Targets pulsed with low avidity mutant antigens frequently escaped while CTLs killed targets bearing high avidity antigen with near-perfect efficiency. CTLs engaged, arrested, and killed an initial target bearing high avidity antigen within minutes, but serial killing was surprisingly rare. CD8 cells remained committed to their initial dead target for hours, accumulating TCR signals that sustained secretion of soluble antiviral factors. These data indicate that high-avidity CD8+ T-cells execute an antiviral program in the precise location where antigen has been sensed: CTL effector functions are spatiotemporally coordinated with an early lytic phase followed by a sustained stationary secretory phase to control local viral infection

A coupled hydrology-biogeochemistry model to simulate dissolved organic carbon exports from a permafrost influenced catchment

Funded by Natural Environment Research Council. Grant Number: NE/K000268/1 Natural Sciences and Engineering Research Council of CanadaPeer reviewedPublisher PD

Sustained antigen availability during germinal center initiation enhances antibody responses to vaccination

Natural infections expose the immune system to escalating antigen and inflammation over days to weeks, whereas nonlive vaccines are single bolus events. We explored whether the immune system responds optimally to antigen kinetics most similar to replicating infections, rather than a bolus dose. Using HIV antigens, we found that administering a given total dose of antigen and adjuvant over 1–2 wk through repeated injections or osmotic pumps enhanced humoral responses, with exponentially increasing (exp-inc) dosing profiles eliciting >10-fold increases in antibody production relative to bolus vaccination post prime. Computational modeling of the germinal center response suggested that antigen availability as higher-affinity antibodies evolve enhances antigen capture in lymph nodes. Consistent with these predictions, we found that exp-inc dosing led to prolonged antigen retention in lymph nodes and increased Tfh cell and germinal center B-cell numbers. Thus, regulating the antigen and adjuvant kinetics may enable increased vaccine potency.National Institute of Allergy and Infectious Diseases (U.S.) (Awards UM1AI100663)National Institute of Allergy and Infectious Diseases (U.S.) (Awards AI110657

The Lion's Roar, North Texas Junior High, 1968-1969, Denton, Texas, Volume 17

Yearbook for North Texas Junior High School in Denton, Texas includes photos of and information about the school, student body, teachers, and organizations