CD4+ T Cell Effects on CD8+ T Cell Location Defined Using Bioluminescence

T lymphocytes of the CD8+ class are critical in delivering cytotoxic function and in controlling viral and intracellular infections. These cells are “helped” by T lymphocytes of the CD4+ class, which facilitate their activation, clonal expansion, full differentiation and the persistence of memory. In this study we investigated the impact of CD4+ T cells on the location of CD8+ T cells, using antibody-mediated CD4+ T cell depletion and imaging the antigen-driven redistribution of bioluminescent CD8+ T cells in living mice. We documented that CD4+ T cells influence the biodistribution of CD8+ T cells, favoring their localization to abdominal lymph nodes. Flow cytometric analysis revealed that this was associated with an increase in the expression of specific integrins. The presence of CD4+ T cells at the time of initial CD8+ T cell activation also influences their biodistribution in the memory phase. Based on these results, we propose the model that one of the functions of CD4+ T cell “help” is to program the homing potential of CD8+ T cells

Correlation Of Ultrasound-Induced Hemolysis With Cavitation Detector Output In Vitro

A 20-MHz passive acoustic detector was used to quantify the amount of transient acoustic cavitation occurring in a sample exposed to intense pulsed ultrasound, A dilute suspension of human erythrocytes with and without a microbubble echo-contrast agent was exposed in vitro to 500 W/cm(2) (SPPA) ultrasound of center frequency 1 MHz and tone burst duration 20, 100, 200, 500 and 1000 mu s at a pulse repetition frequency of 20 Hz. Inertial cavitation occurring within the sample, as measured by the temporal average of the detector output, correlated well with hemolysis, suggesting that violent bubble collapse is responsible for cell damage, The result also raises the prospect of cavitation monitoring as a possible predictor of adverse bioeffects when echo-contrast agents are used clinically. (C) 1997 World Federation for Ultrasound in Medicine & Biology

Effects of Neddylation and mTOR Inhibition in Acute Myelogenous Leukemia

Acute myelogenous leukemia (AML) is a heterogeneous disease and often relapses after standard chemotherapy. Recently, the neddylation (NEDD8) and the mammalian target of rapamycin (mTOR) signaling pathways have emerged as promising pharmaceutical targets for AML therapy. However, the interaction of these two pathways remains unclear. Here we evaluated the effects of pevonedistat, an inhibitor of the NEDD8 activating enzyme (NAE), and sapanisertib (TAK-228), an inhibitor of mTORC1 and mTORC2 as single agents or in combination on AML cell lines. We found that inhibition of neddylation with pevonedistat partially inhibited mTOR signaling transduction and vice versa, inhibition of mTOR signaling with sapanisertib partially inhibited neddylation in AML cell lines. Pevonedistat alone was able to induce cytotoxicity in most AML cell lines as well as in primary AML, whereas sapanisertib alone decreased cell metabolic activity, reduced cell size and arrested cells in G0 phase with only minimal induction of cell death. In addition, pevonedistat was able to induce cell differentiation, arrest cells in G2/M cell cycle phases, and induce DNA re-replication and damage. However, co-treatment with sapanisertib suppressed pevonedistat induced apoptosis, differentiation, S/G2/M arrest, and DNA damage. Taken together, our data demonstrate that pevonedistat and sapanisertib exhibit distinct anti-tumor effects on AML cells, i.e. cytotoxic and cytostatic effects, respectively; however, sapanisertib can attenuate pevonedistat-induced cellular responses in AML cells. Understanding mTOR and neddylation pathway interaction could provide therapeutic strategies for treatment of AML and other malignancies

Effect of a Stabilized Microbubble Echo Contrast Agent on Hemolysis of Human Erythrocytes Exposed to High Intensity Pulsed Ultrasound

Microbubble contrast agents have been shown to enhance ultrasonic cell lysis in vitro when exposed to continuous-wave ultrasound having spatial peak temporal average (SPTA) intensities of a few W/cm2. The response is strongly dependent upon the hematocrit (HCT) of the cell sample; detectable cell lysis essentially disappears as the HCT approaches 5%-10%. This study was conducted to determine whether high intensity pulsedsound is an effective lytic agent in the presence of preexisting potential cavitation nuclei (Albunex® contrast agent). Human erythrocytes weresuspended in autologous plasma to HCTs ranging from 1%–40%. Suspensions were exposed or sham exposed for 60 seconds to focused, pulsed ultrasound. The pulse duration was 1 msec, and the pulse repetition frequency was 20 Hz. The pressure amplitudes, spatial peak pulse average (SPPA) intensity, and SPTA intensity were 4.7 MPa peak positive pressure, -2.7 MPa peak negative pressure, 420 W/cm2, and 8.5 /cm2, respectively. Samples were exposed to ultrasound in a dialysis membrane exposure vessel rotating at 200 rpm. When included in the erythrocyte samples, the Albunex concentration was 35 μL/mL suspension. Significant ultrasound-induced hemolysis in the absence of Albunex was observed only at the lowest HCT value tested (1%). In the presence of Albunex significant cell lysis was observed at all tested HCT values. The relative fraction of cells lysed by the combination of ultrasound exposure and Albunex diminished with increasing HCT, but the number of cells lysed per sample was nearly constant over the range of 5%–40% HCT. The ultrasound exposure parameters used in this study differ substantially from those associated with diagnostic imaging equipment; it is not valid to infer from the present results that the use of Albunex in diagnostic applications will induce or enhance hemolysis in vivo