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951.
The results of the recent Step Study highlight a need to clarify the effects of pre-existing natural immunity to a vaccine vector on vaccine-induced T-cell responses. To investigate this interaction, we examined the relationship between pre-existing Ad5 immunity and T-cell cytokine response profiles in healthy, HIV-uninfected recipients of MRKAd5 HIV-1 gag vaccine (HVTN 050, ClinicalTrials.gov #). Participants were grouped by baseline Ad5 neutralizing antibody titer as either Ad5-seronegative (titer ≤18; n = 36) or Ad5-seropositive (titer >200; n = 34). Samples from vaccine recipients were analyzed for immune responses to either HIV-1 Gag peptide pools or Ad5 empty vector using an ex vivo assay that measures thirty cytokines in the absence of long-term culture. The overall profiles of cytokine responses to Gag and Ad5 had similar combinations of induced Th1- and Th2-type cytokines, including IFN-γ, IL-2, TNF-α, IP-10, IL-13, and IL-10, although the Ad5-specific responses were uniformly higher than the Gag-specific responses (p<0.0001 for 9 out of 11 significantly expressed analytes). At the peak response time point, PBMC from Ad5-seronegative vaccinees secreted significantly more IP-10 in response to Gag (p = 0.008), and significantly more IP-10 (p = 0.0009), IL-2 (p = 0.006) and IL-10 (p = 0.05) in response to Ad5 empty vector than PBMC from Ad5-seropositive vaccinees. Additionally, similar responses to the Ad5 vector prior to vaccination were observed in almost all subjects, regardless of Ad5 neutralizing antibody status, and the levels of secreted IFN-γ, IL-10, IL-1Ra and GM-CSF were blunted following vaccination. The cytokine response profile of Gag-specific T cells mirrored the Ad5-specific response present in all subjects before vaccination, and included a number of Th1- and Th2-associated cytokines not routinely assessed in current vaccine trials, such as IP-10, IL-10, IL-13, and GM-CSF. Together, these results suggest that vector-specific humoral responses may reduce vaccine-induced T-cell responses by previously undetected mechanisms. NCT00849732相似文献
952.
Hammer DX Schmitz H Schmitz A Grady Rylander H Welch AJ 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2001,128(4):129-819
The minimum detection threshold of the infrared sensitive beetle, Melanophila acuminata, was measured with a helium-neon laser that emitted light at a wavelength of 3.39 microm. Extracellular recordings were taken both at the pit organ responsible for detection and at the interganglionic connectives in the thorax of the beetle. At the pit organ, generator and action potentials from single neurons were measured with a sharpened tungsten electrode. At the connectives that linked the fused second meso-/metathoracic and prothoracic ganglia, compound action potentials were measured with a tungsten hook electrode that encircled the connective. The latter recordings confirmed conveyance of infrared information through specific pathways to rostrally-situated sites in the nervous system of the beetle. The 50% probability irradiance threshold at which action potentials were elicited from the receptor and connectives occurred at 17.3 and 14.6 mW/cm(2), respectively. In addition to sensitivity threshold, several other characteristics of the response were quantified including dependence of generator potential latency, generator potential duration, spike frequency, and spike latency on irradiance, dependence of response strength (spike count) on exposure time, and flicker fusion frequency. The ability to detect infrared radiation is rare in nature, and these results provide valuable information necessary to understand this unique sensitivity. 相似文献
953.
An automated assay for measuring nanogram and subnanogram quantities of protein in microliter samples was developed with the fluorometric reagent omicron-phthaldialdehyde/mercaptoethanol. Low molecular weight interfering substances were separated within the analysis by gel filtration. The technique allowed measurement of biological fluids without any sample pretreatment. The method presented proved to be linear within the range 1.2 ng to 1.4 microgram with a standard deviation of +/- 4.2%. The minimum detectable protein concentration was 1 microgram/liter. Special care was taken to prevent any determination errors caused by losses of protein during adsorption to surfaces. The simple analytical apparatus constructed can be used for field studies and ran several weeks when continuously used for seawater analysis aboard ship. 相似文献
954.
Becher D Specht M Hammer E Francke W Schauer F 《Applied and environmental microbiology》2000,66(10):4528-4531
Cells of the gram-negative bacterium Ralstonia sp. strain SBUG 290 grown in the presence of biphenyl are able to cooxidize dibenzofuran which has been 1,2-hydroxylated. Meta cleavage of the 1, 2-dihydroxydibenzofuran between carbon atoms 1 and 9b produced 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, which was degraded completely via salicylic acid. The presence of these intermediates indicates a degradation mechanism for dibenzofuran via lateral dioxygenation by Ralstonia sp. strain SBUG 290. 相似文献
955.
Christian Solli Marte Reenaas Anders Hammer Strømman Edgar G. Hertwich 《The International Journal of Life Cycle Assessment》2009,14(6):517-528
Background, aim, and scope
In this study, we evaluate the environmental effects of wood-based household heating. Wood is a significant source of household heating in Norway, and a comparative life cycle assessment of a wood-based heating system using an old and a modern stove was conducted to estimate the total life cycle benefits associated with the change from old to new combustion technology. 相似文献956.
957.
Dooyoung Lee Kelly E. Caputo Daniel A. Hammer Michael R. King 《Journal of theoretical biology》2009,260(1):27-30
Here we accurately recreate the mechanical shedding of L-selectin and its effect on the rolling behavior of neutrophils in vitro using the adhesive dynamics simulation by incorporating the shear-dependent shedding of L-selectin. We have previously shown that constitutively expressed L-selectin is cleaved from the neutrophil surface during rolling on a sialyl Lewis x-coated planar surface at physiological shear rates without the addition of exogenous stimuli. Utilizing a Bell-like model to describe a shedding rate which presumably increases exponentially with force, we were able to reconstruct the characteristics of L-selectin-mediated neutrophil rolling observed in the experiments. First, the rolling velocity was found to increase during rolling due to the mechanical shedding of L-selectin. When most of the L-selectin concentrated on the tips of deformable microvilli was cleaved by force exerted on the L-selectin bonds, the cell detached from the reactive plane to join the free stream as observed in the experiments. In summary, we show through detailed computational modeling that the force-dependent shedding of L-selectin can explain the rolling behavior of neutrophils mediated by L-selectin in vitro. 相似文献
958.
There has been increasing concern over As in freshwater environments from sources such as arsenical pesticides, smelters,
coal-fired power plants, and erosion caused by intensive land use. Arsenic in the reduced state, As (III) (arsenite), is much
more toxic, more soluble and mobile, than when in the oxidized state, As (V) (arsenate). This paper summarizes the dynamics
and mechanisms involved in the oxidation of As (III) to As (V) by freshwater lake sediments. Sediments from selected freshwater
lakes in southern Saskatchewan oxidize As (III) to As (V) predominantly through an abiotic process. Solution analysis of As
(III) and As (V) by colorimetry, and examination of the oxidation state of surface-sorbed As species by X-ray photoelectron
spectroscopy, indicate that Mn present in the sediment is the primary electron acceptor in the oxidation of As (III). The
transformation of As (III) to As (V) by carbonate and silicate minerals, common in sediments, is not evident. The heat of
activation, ΔHa, for the depletion (oxidation plus sorption) of As (III) by the sediments, varies from 3.3 to 8.5 kcal mole−1, indicating that the process is predominantly diffusion-controlled. The Mn present in a series of particle size fractions
( < 2– > 20 μm) of the sediments may potentially detoxify As (III) in aquatic systems, by converting it to As (V). 相似文献
959.
960.