E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following 48Ca + 208Pb, 48Ca + 238U, and 64Ni + 238U reactions. By exploiting delayedand cross-coincidence techniques, level schemes have been delineated in odd 119-125Sn isotopes. Particular attention was paid to the occurrence of 19/2+ and 23/2+ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudes for the seniority ν = 2 and 3, 10+ and 27/2- isomers in even- and odd-Sn isotopes, respectively

High-seniority excitations in even neutron-rich sn isotopes populated in fusion-fission reactions

High-seniority excitations above the 10+ and 27=2-isomeric states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following 48Ca+208Pb, 48Ca+238U and 64Ni+238U reactions. In the data analysis, the delayed gamma coincidence technique was used to establish high-spin state structures in all Sn isotopes with isomeric half-lives below 10 sec. For cases with long-lived isomeric states, the gamma cross-coincidence method was employed to identify such structures. The relevant features of the fusion-fission process were investigated to enable these identifications. The discussion of some details of these analyses is followed by two examples of the results obtained: the 124Sn level scheme and the level energy systematics for selected states established in even Sn isotopes

Targeted calcium influx boosts cytotoxic T lymphocyte function in the tumour microenvironment

Adoptive cell transfer utilizing tumour-targeting cytotoxic T lymphocytes (CTLs) is one of the most effective immunotherapies against haematological malignancies, but significant clinical success has not yet been achieved in solid tumours due in part to the strong immunosuppressive tumour microenvironment. Here, we show that suppression of CTL killing by CD4+CD25+Foxp+ regulatory T cell (Treg) is in part mediated by TGFβ-induced inhibition of inositol trisphosphate (IP3) production, leading to a decrease in T cell receptor (TCR)-dependent intracellular Ca2+ response. Highly selective optical control of Ca2+ signalling in adoptively transferred CTLs enhances T cell activation and IFN-γ production in vitro, leading to a significant reduction in tumour growth in mice. Altogether, our findings indicate that the targeted optogenetic stimulation of intracellular Ca2+ signal allows for the remote control of cytotoxic effector functions of adoptively transferred T cells with outstanding spatial resolution by boosting T cell immune responses at the tumour sites

High-spin shell model states in neutron-rich Sn isotopes

High-spin states with the seniority v ≥ 2 have been investigated in the neutron-rich 118,120,122,124,126Sn isotopes. They were produced in fusion-fission processes following 48Ca + 208Pb, 48Ca + 238U reactions and via fission of target nuclei in the 64Ni + 238U system. By employing techniques of delayed- and cross-coincidences, it was possible to establish level schemes up to an 8 MeV excitation energy. The 13- and 15- states were identified as being isomeric and their half-lives were determined. The reduced transition probabilities extracted for isomeric transitions behave very regularly with the mass number A. The spin-parity values assigned to or suggested for the identified states were supported by shell-model calculations and by systematics

Histone deacetylase 1 and 2 differentially regulate apoptosis by opposing effects on extracellular signal-regulated kinase 1/2

Histone deacetylases (HDACs) are epigenetic regulators that are important for the control of various pathophysiological events. We found that HDAC inhibitors completely abolished transforming growth factor-β1 (TGF-β1)-induced apoptosis in AML-12 and primary mouse hepatocytes. Expression of a dominant-negative mutant of HDAC1 or downregulation of HDAC1 by RNAi both suppressed TGF-β1-induced apoptosis. In addition, overexpression of HDAC1 enhanced TGF-β1-induced apoptosis, and the rescue of HDAC1 expression in HDAC1 RNAi cells restored the apoptotic response of cells to TGF-β1. These data indicate that HDAC1 functions as a proapoptotic factor in TGF-β1-induced apoptosis. In contrast, downregulation of HDAC2 by RNAi increased spontaneous apoptosis and markedly enhanced TGF-β1-induced apoptosis, suggesting that HDAC2 has a reciprocal role in controlling cell survival. Furthermore, inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) by MEK1 inhibitor PD98059 or expression of a kinase-dead mutant of MEK1 restored the apoptotic response to TGF-β1 in HDAC1 RNAi cells. Strikingly, HDAC2 RNAi caused an inhibition of ERK1/2, and the spontaneous apoptosis can be abolished by reactivation of ERK1/2. Taken together, our data demonstrate that HDAC1 and 2 reciprocally affect cell viability by differential regulation of ERK1/2; these observations provide insight into the roles and potential mechanisms of HDAC1 and 2 in apoptosis

Levels above the 19/2- isomer in Cu71: Persistence of the N=40 neutron shell gap

Two prompt γ rays of energies 2020 and 554 keV were observed in coincidence with delayed transitions depopulating the 19/2- isomer in the Z=29, N=42 Cu71 nucleus. The newly identified transitions are proposed to deexcite the 4776- and 5330-keV levels above the 19/2- isomer. Based on the comparison with the low-lying positive-parity states observed in the Z=42, N=50 Mo92 nucleus, spin and parity 23/2- are proposed for the 4776-keV level in Cu71. The high-energy, 2020-keV transition is interpreted as arising from the breaking of the N=40 neutron core. Shell-model calculations with a Ni56 core reproduce the (23/2-)→(19/2-) gap well, suggesting that the 23/2- state is dominated by πp3/2ν((fp)10(g9/2)4) configurations. The present result constitutes further evidence supporting the view that the N=40 subshell closure persists in Cu71, herewith challenging recent suggestions that the coupling of two or more proton or neutron quasiparticles induces a large polarization of the Ni68 core

Higher-seniority excitations in even neutron-rich Sn isotopes

Excited states above the seniority ν=2 isomers have been investigated in even neutron-rich 118-128Sn isotopes produced by fusion-fission of 6.9 MeV/A Ca48 beams with Pb208 and U238 targets and by fission of 6.7 MeV/A Ni64 beams on a U238 target. Level schemes up to excitation energies in excess of 8 MeV have been established based on multifold γ-ray coincidence relationships measured with the Gammasphere array. Isotopic identification of crucial transitions was achieved through a number of techniques, including prompt and delayed cross-coincidence methods. As a result, seniority ν=4, 15-, and 13- isomers were observed and their half-lives determined. These long-lived states in turn served as steppingstones to delineate the isomeric decays and to locate higher-lying states with good sensitivity. As the observed isomeric decays feed down to 10+ and 7- isomers, firm spin-parity assignments could be proposed for most of the seniority ν=4 states. Higher-lying, seniority ν=6 levels were assigned tentatively on the basis of the observed deexcitation paths as well as of general yrast population arguments. Shell-model calculations were carried out down to Sn122 in the g7/2, d5/2, d3/2, s1/2, and h11/2 model space of neutron holes with respect to a Sn132 core. Effective two-body interactions were adjusted such that satisfactory agreement with data was achieved for Sn130. The results reproduce the experimental level energies and spin-parity assignments rather well. The intrinsic structure of the states is discussed on the basis of the calculated wave functions which, in many instances, point to complex configurations. In a few cases, the proposed assignments lead to unresolved issues. The smooth, systematic decrease of the level energies with mass A is accompanied by the similarly regular behavior with A of the reduced transition probabilities extracted from the isomeric half-lives. This A dependence is discussed for the E1 and E2 transitions in the decay of the seniority ν=4 isomers and is compared to that determined in earlier work for the E2 transition rates from the ν=2,3 isomers