504 research outputs found
Autocrine production of extracellular catalase prevents apoptosis of the human CEM T-cell line in serum-free medium.
CCRF-CEM is a human T-cell line originally isolated from a child with acute lymphoblastic leukemia. At cell densities > 2 x 10 cells per ml, CEM cells grow in serum-free medium, but at lower cell densities the cultures rapidly undergo apoptosis, or programmed cell death. The viability of lowdensity CEM cells could be preserved by supplementing the serum-free medium with "conditioned" medium from highdensity CEM cultures, but a variety of known growth factors and lymphokines were ineffective. Fractionation ofconditioned medium by sequential chromatography on DEAE-cellulose, propyl agarose, chromatofocusing, and hydrophobic-interaction HPLC resulted in the isolation of a 60-kDa protein capable of sustaining CEM growth in the absence ofserum. The active protein was identified as human catalase based on its amino acid sequence and composition and was subsequently shown to exhibit catalase activity and to be replaceable by human erythrocyte catalase or bovine liver catalase. Comparison of the level of intracellular catalase activity with the amount released into the culture medium demonstrated that the latter accounted for <3% of the total catalase activity present in the cell culture. These findings show that, despite its low amount, the catalase released by CEM cells, and perhaps by T cells in general, provides a critical rust Ilne of defense against hydrogen peroxide (11202) present in the extracellular milieu. Originally published Proceedings of the National Academy of Sciences, Vol. 90, No. 10, May 199
Scientific Visualization Using the Flow Analysis Software Toolkit (FAST)
Over the past few years the Flow Analysis Software Toolkit (FAST) has matured into a useful tool for visualizing and analyzing scientific data on high-performance graphics workstations. Originally designed for visualizing the results of fluid dynamics research, FAST has demonstrated its flexibility by being used in several other areas of scientific research. These research areas include earth and space sciences, acid rain and ozone modelling, and automotive design, just to name a few. This paper describes the current status of FAST, including the basic concepts, architecture, existing functionality and features, and some of the known applications for which FAST is being used. A few of the applications, by both NASA and non-NASA agencies, are outlined in more detail. Described in the Outlines are the goals of each visualization project, the techniques or 'tricks' used lo produce the desired results, and custom modifications to FAST, if any, done to further enhance the analysis. Some of the future directions for FAST are also described
Radio Interferometric Planet Search II: Constraints on sub-Jupiter-Mass Companions to GJ 896A
We present results from the Radio Interferometric Planet (RIPL) search for
compan- ions to the nearby star GJ 896A. We present 11 observations over 4.9
years. Fitting astrometric parameters to the data reveals a residual with
peak-to-peak amplitude of ~ 3 mas in right ascension. This residual is well-fit
by an acceleration term of 0.458 \pm 0.032 mas/y^2. The parallax is fit to an
accuracy of 0.2 mas and the proper motion terms are fit to accuracies of 0.01
mas/y. After fitting astrometric and acceleration terms residuals are 0.26 mas
in each coordinate, demonstrating that stellar jitter does not limit the
ability to carry out radio astrometric planet detection and characterization.
The acceleration term originates in part from the companion GJ 896B but the
amplitude of the acceleration in declination is not accurately predicted by the
orbital model. The acceleration sets a mass upper limit of 0.15 MJ at a
semi-major axis of 2 AU for a planetary companion to GJ 896A. For semi-major
axes between 0.3 and 2 AU upper limits are determined by the maximum angular
separation; the upper limits scale from the minimum value in proportion to the
inverse of the radius. Upper limits at larger radii are set by the acceleration
and scale as the radius squared. An improved solution for the stellar binary
system could improve the exoplanet mass sensitivity by an order of magnitude.Comment: Accepted for publication in Ap
The Origins of [CII] Emission in Local Star-forming Galaxies
The [CII] 158um fine-structure line is the brightest emission line observed
in local star-forming galaxies. As a major coolant of the gas-phase
interstellar medium, [CII] balances the heating, including that due to
far-ultraviolet photons, which heat the gas via the photoelectric effect.
However, the origin of [CII] emission remains unclear, because C+ can be found
in multiple phases of the interstellar medium. Here we measure the fractions of
[CII] emission originating in the ionized and neutral gas phases of a sample of
nearby galaxies. We use the [NII] 205um fine-structure line to trace the
ionized medium, thereby eliminating the strong density dependence that exists
in the ratio of [CII]/[NII] 122um. Using the FIR [CII] and [NII] emission
detected by the KINGFISH and Beyond the Peak Herschel programs, we show that
60-80% of [CII] emission originates from neutral gas. We find that the fraction
of [CII] originating in the neutral medium has a weak dependence on dust
temperature and the surface density of star formation, and a stronger
dependence on the gas-phase metallicity. In metal-rich environments, the
relatively cooler ionized gas makes substantially larger contributions to total
[CII] emission than at low abundance, contrary to prior expectations.
Approximate calibrations of this metallicity trend are provided.Comment: 8 pages, accepted for publication in Ap
Evolutionary Status of Brightest and Youngest Source in the Orion Molecular Cloud-3 Region
The brightest continuum source in the Orion Molecular Cloud-3 region (OMC-3),
MMS 6, was observed with the Very Large Array (VLA), the Nobeyama Millimeter
Array (NMA), and the Submillimeter Array (SMA). Our data were supplemented by
near- to mid-infrared archival data taken by Spitzer Space Telescope. The
compact continuum source, MMS 6-main, was detected with an H_2 mass of 3.0 Msun
with a size of 510 AU. Despite its compact and well condensed appearance,
neither clear CO outflow, radio jet, nor infrared sources (at a wave-length
shorter than 8 um) were detected at MMS 6-main even with the present
high-spatial resolution and high-sensitivity observations. The derived H_2
column density, 2.6x10^25 cm^-2, corresponds to a visual extinction of
A_v~15000 mag., and the derived number density is at least two orders of
magnitude higher than for the other OMC-2/3 continuum sources. The volume
density profile of the source was estimated to have a power-law index of 2 or
steeper down to a radius of ~450 AU. The time scale to form a protostar at the
center or the time scale elapsed after its formation is estimated to be 830 to
7600 yr. This is much shorter than the typical lifetime of the Class 0/I
protostars, which is ~10^(4-5) yr, suggesting that MMS 6-main is probably in
either the earliest stage of the proto-stellar core or in the latest stage of
the pre-stellar phase.Comment: 34 pages, 7 figures, accepted to Ap
The role of Zn-OR and Zn-OH nucleophiles and the influence of para-substituents in the reactions of binuclear phosphatase mimetics
Analogues of the ligand 2,2'-(2-hydroxy-5-methyl-1,3-phenylene)bis(methylene)bis((pyridin-2-ylmethyl)azanediyl)diethanol (CH(3)H(3)L1) are described. Complexation of these analogues, 2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol (CH(3)HL2), 4-bromo-2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (BrHL2), 2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)-4-nitrophenol (NO(2)HL2) and 4-methyl-2,6-bis(((2-phenoxyethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (CH(3)HL3) with zinc(II) acetate afforded [Zn-2(CH(3)L2)(CH3COO)(2)](PF6), [Zn-2(NO(2)L2)(CH3COO)(2)](PF6), [Zn-2(BrL2)(CH3COO)(2)](PF6) and [Zn-2(CH(3)L3)(CH3COO)(2)](PF6), in addition to [Zn-4(CH(3)L2)(2)(NO2C6H5OPO3)(2)(H2O)(2)](PF6)(2) and [Zn-4(BrL2)(2)(PO3F)(2)(H2O)(2)](PF6)(2). The complexes were characterized using H-1 and C-13 NMR spectroscopy, mass spectrometry, microanalysis, and X-ray crystallography. The complexes contain either a coordinated methyl-(L2 ligands) or phenyl-(L3 ligand) ether, replacing the potentially nucleophilic coordinated alcohol in the previously reported complex [Zn-2(CH(3)HL1)(CH3COO)(H2O)](PF6). Functional studies of the zinc complexes with the substrate bis(2,4-dinitrophenyl) phosphate (BDNPP) showed them to be competent catalysts with, for example, [Zn-2(CH(3)L2)](+), k(cat) = 5.70 +/- 0.04 x 10(-3) s(-1) (K-m = 20.8 +/- 5.0 mM) and [Zn-2(CH(3)L3)](+), kcat = 3.60 +/- 0.04 x 10(-3) s(-1) (K-m = 18.9 +/- 3.5 mM). Catalytically relevant pK(a)s of 6.7 and 7.7 were observed for the zinc(II) complexes of CH(3)L2(-) and CH(3)L3(-), respectively. Electron donating para-substituents enhance the rate of hydrolysis of BDNPP such that k(cat) p-CH3 > p-Br > p-NO2. Use of a solvent mixture containing H2O18/H2O16 in the reaction with BDNPP showed that for [Zn-2(CH(3)L2)(CH3COO)(2)](PF6) and [Zn-2(NO(2)L2)(CH3COO)(2)](PF6), as well as [Zn-2(CH(3)HL1)(CH3COO)(H2O)](PF6), the O-18 label was incorporated in the product of the hydrolysis suggesting that the nucleophile involved in the hydrolysis reaction was a Zn-OH moiety. The results are discussed with respect to the potential nucleophilic species (coordinated deprotonated alcohol versus coordinated hydroxide)
Recommended from our members
Effectiveness of Trauma-Focused Psychological Therapies for Treating Post-traumatic Stress Disorder Symptoms in Women Following Childbirth: A Systematic Review and Meta-Analysis.
Background: Approximately 3% of women in community samples develop posttraumatic stress disorder (PTSD) after childbirth. Higher prevalence rates are reported for high risk samples. Postpartum PTSD can adversely affect women's wellbeing, mother-infant relationships and child development. This study aims to examine the effectiveness of trauma-focused psychological interventions (TFPT), for postnatal women.
Methods: We conducted a systematic review and meta-analysis including all clinical trials which reported post-traumatic stress symptoms for both the intervention and control groups or at least two time-points, pre- and post-intervention. We searched four databases: CENTRAL, MEDLINE, PsycINFO, and OpenGrey. Screening of search results, data extraction, and risk of bias assessment were undertaken independently by two reviewers.
Results: Eleven studies, reported in 12 papers, involving 2,677 postnatal women were included. All were RCTs, bar one case series. Interventions varied in modality, duration and intensity, and included exposure therapy, trauma-focused cognitive behavioral therapy, eye movement desensitization and reprocessing and other psychological approaches. Participants had experienced uncomplicated births, emergency cesarean sections and/or preterm births. Results suggest that TFPT are effective for reducing PTSD symptoms in the short term (up to 3 months postpartum [4 RCTs, n = 301, SMD = −0.50, 95% CI = −0.73 to −0.27]), and medium term (i.e., 3–6 months postpartum [2 RCTs, n = 174, SMD = −1.87, 95% CI = −2.60 to −1.13]). However, there is no robust evidence to suggest whether TFPT can also improve women's recovery from clinically significant PTSD symptoms.
Conclusion: Further larger studies, distinguishing between low and high risk groups, and with adequate follow-up, are needed to establish which TFPT are most effective and acceptable for treating postnatal PTSD
IceCube-Gen2: A Vision for the Future of Neutrino Astronomy in Antarctica
The recent observation by the IceCube neutrino observatory of an
astrophysical flux of neutrinos represents the "first light" in the nascent
field of neutrino astronomy. The observed diffuse neutrino flux seems to
suggest a much larger level of hadronic activity in the non-thermal universe
than previously thought and suggests a rich discovery potential for a larger
neutrino observatory. This document presents a vision for an substantial
expansion of the current IceCube detector, IceCube-Gen2, including the aim of
instrumenting a volume of clear glacial ice at the South
Pole to deliver substantial increases in the astrophysical neutrino sample for
all flavors. A detector of this size would have a rich physics program with the
goal to resolve the sources of these astrophysical neutrinos, discover GZK
neutrinos, and be a leading observatory in future multi-messenger astronomy
programs.Comment: 20 pages, 12 figures. Address correspondence to: E. Blaufuss, F.
Halzen, C. Kopper (Changed to add one missing author, no other changes from
initial version.
- …
