416 research outputs found
Different cytokine profiles released by CD4+ and CD8+ tumorâdraining lymph node cells involved in mediating tumor regression
We have previously demonstrated that the growth of weakly immunogenic murine sarcomas leads to the induction of immunologically specific preeffector cells in tumorâdraining lymph nodes (TDLN). The in vitro activation of TDLN cells with antiâCD3 monoclonal antibodies (mAbs) and interleukinâ2 (ILâ2) resulted in the acquisition of effector function as measured by tumor regression in the adoptive immunotherapy of pulmonary metastases. Further studies were performed to characterize the mechanisms associated with in vivo tumor reactivity mediated by activated TDLN cells. By positive selection, CD4+ and CD8+ T cells were purified and activated by the antiâCD3/ILâ2 method. CD8+, but not CD4+, cells manifested tumorâspecific granulocyteâmacrophage colonyâstimulating factor (GMâCSF) and interferonâÎł (IFNâÎł) release in vitro, and elicited tumor regression in vivo. By contrast, only activated CD4+ were found to release significant amounts of ILâ2 in response to tumor antigen but did not mediate tumor regression in vivo. Mixing the two purified populations enhanced the antitumor activity of the CD8+ T cells. In culture, ILâ2 was found to augment the relative amount of tumorâspecific release of GMâCSF and IFNâÎł by activated TDLN cells. We found that the tumorâspecific release of GMâCSF and IFNâÎł by activated lymphocytes was strongly associated with the in vivo therapeutic efficacy of these cells. Evidence in support of this included the following: (1) cytokine release of TDLN derived after different durations of tumor growth correlated with tumor reactivity in adoptive transfer studies, (2) cytokine release of T cells derived from different lymphoid organs corresponded with tumor reactivity in adoptive transfer, and (3) in vivo administration of neutralizing mAb to IFNâÎł and GMâCSF significantly inhibited the antitumor reactivity of TDLN cells. These studies document the contributory roles of IFNâÎł, GMâCSF, and ILâ2 released by activated CD4+ and CD8+ T cells involved in tumor regression. J. Leukoc. Biol. 61: 507â516; 1997.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142128/1/jlb0507.pd
Xenopus Zic3 controls notochord and organizer development through suppression of the Wnt/β-catenin signaling pathway
AbstractZic3 controls neuroectodermal differentiation and leftâright patterning in Xenopus laevis embryos. Here we demonstrate that Zic3 can suppress Wnt/β-catenin signaling and control development of the notochord and Spemann's organizer. When we overexpressed Zic3 by injecting its RNA into the dorsal marginal zone of 2-cell-stage embryos, the embryos lost mesodermal dorsal midline structures and showed reduced expression of organizer markers (Siamois and Goosecoid) and a notochord marker (Xnot). Co-injection of Siamois RNA partially rescued the reduction of Xnot expression caused by Zic3 overexpression. Because the expression of Siamois in the organizer region is controlled by Wnt/β-catenin signaling, we subsequently examined the functional interaction between Zic3 and Wnt signaling. Co-injection of Xenopus Zic RNAs and β-catenin RNA with a reporter responsive to the Wnt/β-catenin cascade indicated that Zic1, Zic2, Zic3, Zic4, and Zic5 can all suppress β-catenin-mediated transcriptional activation. In addition, co-injection of Zic3 RNA inhibited the secondary axis formation caused by ventral-side injection of β-catenin RNA in Xenopus embryos. Zic3-mediated Wnt/β-catenin signal suppression required the nuclear localization of Zic3, and involved the reduction of β-catenin nuclear transport and enhancement of β-catenin degradation. Furthermore, Zic3 co-precipitated with Tcf1 (a β-catenin co-factor) and XIC (I-mfa domain containing factor required for dorsoanterior development). The findings in this report produce a novel system for fine-tuning of Wnt/β-catenin signaling
The structure of K- and Cs-monolayers on Cu(0 0 1): diffraction experiments far from the Bragg point
The intensity analysis along the crystal truncation rods has been used to analyse in situ the adsorption behaviour and the structure of K and Cs on Cu(0 0 1) at submonolayer coverages and room temperature. Up to about 0.25 ML K atoms adsorb in hollow sites followed by formation of a quasihexagonal superstructure. In contrast, for Cs adsorption the data can be interpreted by the formation of quasihexagonal Cs islands that grow with increasing coverage. For K an effective radius of 1.6(1) Ă
independent of coverage is determined. For Cs we fnd d = 2.1 (1) Ă
after formation of the quasihexagonal superstructure
Frustrated minority spins in GeNi2O4
Recently, two consecutive phase transitions were observed, upon cooling, in
an antiferromagnetic spinel GeNiO at K and
K, respectively \cite{matsuno, crawford}. Using unpolarized and polarized
elastic neutron scattering we show that the two transitions are due to the
existence of frustrated minority spins in this compound. Upon cooling, at
the spins on the \kagome planes order ferromagnetically in the
plane and antiferromagnetically between the planes (phase I), leaving the spins
on the triangular planes that separate the \kagome planes frustrated
and disordered. At the lower , the triangular spins also order in the
plane (phase II). We also present a scenario involving exchange
interactions that qualitatively explains the origin of the two purely magnetic
phase transitions
Expression of ZIC family genes in meningiomas and other brain tumors
<p>Abstract</p> <p>Background</p> <p>Zic zinc finger proteins are present in the developing rodent meninges and are required for cell proliferation and differentiation of meningeal progenitors. Although human <it>ZIC </it>genes are known to be molecular markers for medulloblastomas, their expression in meningioma has not been addressed to date.</p> <p>Methods</p> <p>We examined the mRNA and protein expression of human <it>ZIC1</it>, <it>ZIC2</it>, <it>ZIC3</it>, <it>ZIC4 </it>and <it>ZIC5 </it>genes in meningiomas in comparison to other brain tumors, using RT-PCR, analysis of published microarray data, and immunostaining.</p> <p>Results</p> <p><it>ZIC1</it>, <it>ZIC2 </it>and <it>ZIC5 </it>transcript levels in meningiomas were higher than those in whole brain or normal dura mater, whereas all five <it>ZIC </it>genes were abundantly expressed in medulloblastomas. The expression level of <it>ZIC1 </it>in public microarray data was greater in meningiomas classified as World Health Organization Grade II (atypical) than those classified as Grade I (benign). Immunoscreening using anti-ZIC antibodies revealed that 23 out of 23 meningioma cases were ZIC1/2/3/5-immunopositive. By comparison, nuclear staining by the anti-ZIC4 antibody was not observed in any meningioma case, but was strongly detected in all four medulloblastomas. ZIC-positive meningiomas included meningothelial, fibrous, transitional, and psammomatous histological subtypes. In normal meninges, ZIC-like immunoreactivities were detected in vimentin-expressing arachnoid cells both in human and mouse.</p> <p>Conclusions</p> <p>ZIC1, ZIC2, and ZIC5 are novel molecular markers for meningiomas whereas <it>ZIC4 </it>expression is highly selective for medulloblastomas. The pattern of <it>ZIC </it>expression in both of these tumor types may reflect the properties of the tissues from which the tumors are derived.</p
Electronic and Magnetic Properties of Febr2
Electronic and magnetic (e-m) properties of FeBr2 have been surprisingly well
described as originating from the Fe2+ ions and their fine electronic
structure. The fine electronic structure have been evaluated taking into
account the spin-orbit (s-o) coupling, crystal-field and inter-site
spin-dependent interactions. The required magnetic doublet ground state with an
excited singlet at D=2.8 meV results from the trigonal distortion. This effect
of the trigonal distortion and a large magnetic moment of iron, of 4.4 mB, can
be theoretically derived provided the s-o coupling is correctly taking into
account. The obtained good agreement with experimental data indicates on
extremaly strong correlations of the six 3d electrons in the Fe2+ ion yielding
their full localization and the insulating state. These calculations show that
for the meaningful analysis of e-m properties of FeBr2 the spin-orbit coupling
is essentially important and that the orbital moment (0.74 mB) is largely
unquenched (by the off-cubic trigonal distortion in the presence of the
spin-orbit coupling).Comment: 11 pages in RevTex, 5 figure
Aging, rejuvenation and memory effects in Ising and Heisenberg spin glasses
We have compared aging phenomena in the Fe_{0.5}Mn_{0.5}TiO_3 Ising spin
glass and in the CdCr_{1.7}In_{0.3}S_4 Heisenberg-like spin glass by means of
low-frequency ac susceptibility measurements. At constant temperature, aging
obeys the same ` scaling' in both samples as in other systems.
Investigating the effect of temperature variations, we find that the Ising
sample exhibits rejuvenation and memory effects which are qualitatively similar
to those found in other spin glasses, indicating that the existence of these
phenomena does not depend on the dimensionality of the spins. However,
systematic temperature cycling experiments on both samples show important
quantitative differences. In the Ising sample, the contribution of aging at low
temperature to aging at a slightly higher temperature is much larger than
expected from thermal slowing down. This is at variance with the behaviour
observed until now in other spin glasses, which show the opposite trend of a
free-energy barrier growth as the temperature is decreased. We discuss these
results in terms of a strongly renormalized microscopic attempt time for
thermal activation, and estimate the corresponding values of the barrier
exponent introduced in the scaling theories.Comment: 8 pages, including 6 figure
Spin Glasses: Model systems for non-equilibrium dynamics
Spin glasses are frustrated magnetic systems due to a random distribution of
ferro- and antiferromagnetic interactions. An experimental three dimensional
(3d) spin glass exhibits a second order phase transition to a low temperature
spin glass phase regardless of the spin dimensionality. In addition, the low
temperature phase of Ising and Heisenberg spin glasses exhibits similar
non-equilibrium dynamics and an infinitely slow approach towards a
thermodynamic equilibrium state. There are however significant differences in
the detailed character of the dynamics as to memory and rejuvenation phenomena
and the influence of critical dynamics on the behaviour. In this article, some
aspects of the non-equilibrium dynamics of an Ising and a Heisenberg spin glass
are briefly reviewed and some comparisons are made to other glassy systems that
exhibit magnetic non-equilibrium dynamics.Comment: To appear in J. Phys.: Condens. Matter, Proceedings from HFM2003,
Grenobl
Time and length scales in spin glasses
We discuss the slow, nonequilibrium, dynamics of spin glasses in their glassy
phase. We briefly review the present theoretical understanding of the
spectacular phenomena observed in experiments and describe new numerical
results obtained in the first large-scale simulation of the nonequilibrium
dynamics of the three dimensional Heisenberg spin glass.Comment: Paper presented at "Highly Frustrated Magnetism 2003", Grenoble,
August 200
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