Halo Structure of the Neutron-Dripline Nucleus

The heaviest bound isotope of boron ^{19}B has been investigated using exclusive measurements of its Coulomb dissociation, into ^{17}B and two neutrons, in collisions with Pb at 220 MeV/nucleon. Enhanced electric dipole (E1) strength is observed just above the two-neutron decay threshold with an integrated E1 strength of B(E1)=1.64±0.06(stat)±0.12(sys) e^{2} fm^{2} for relative energies below 6 MeV. This feature, known as a soft E1 excitation, provides the first firm evidence that ^{19}B has a prominent two-neutron halo. Three-body calculations that reproduce the energy spectrum indicate that the valence neutrons have a significant s-wave configuration and exhibit a dineutronlike correlation.

First Observation of

The most neutron-rich boron isotopes ^{20}B and ^{21}B have been observed for the first time following proton removal from ^{22}N and ^{22}C at energies around 230 MeV/nucleon. Both nuclei were found to exist as resonances which were detected through their decay into ^{19}B and one or two neutrons. Two-proton removal from ^{22}N populated a prominent resonancelike structure in ^{20}B at around 2.5 MeV above the one-neutron decay threshold, which is interpreted as arising from the closely spaced 1^{-},2^{-} ground-state doublet predicted by the shell model. In the case of proton removal from ^{22}C, the ^{19}B plus one- and two-neutron channels were consistent with the population of a resonance in ^{21}B 2.47±0.19 MeV above the two-neutron decay threshold, which is found to exhibit direct two-neutron decay. The ground-state mass excesses determined for ^{20,21}B are found to be in agreement with mass surface extrapolations derived within the latest atomic-mass evaluations.

Copolymerisation of ethylene with polar monomers by using palladium catalysts bearing an N-heterocyclic carbene-phosphine oxide bidentate ligand.

We report the synthesis and characterisation of palladium complexes bearing an N-heterocyclic carbene-phosphine oxide bidentate ligand and their use as catalysts for ethylene polymerisation and ethylene/polar monomer copolymerisation.

Nucleus

The unbound nucleus ^{26}O has been investigated using invariant-mass spectroscopy following one-proton removal reaction from a ^{27}F beam at 201 MeV/nucleon. The decay products, ^{24}O and two neutrons, were detected in coincidence using the newly commissioned SAMURAI spectrometer at the RIKEN Radioactive Isotope Beam Factory. The ^{26}O ground-state resonance was found to lie only 18±3(stat)±4(syst) keV above threshold. In addition, a higher lying level, which is most likely the first 2^{+} state, was observed for the first time at 1.28_{-0.08}^{+0.11} MeV above threshold. Comparison with theoretical predictions suggests that three-nucleon forces, pf-shell intruder configurations, and the continuum are key elements to understanding the structure of the most neutron-rich oxygen isotopes beyond the drip line.

Mu rhythm suppression during the imagination of observed action.

Mu wave suppression is thought to accompany the activation of the mirror neuron system which occurs when a human observes or imitates the behavior of others. Our investigation indicates a possible difference in mirror neuron system activation between passive and more active observation as suggested by mu wave activation levels. Participants were asked to observe four different videos each 80 s in duration. Each video was repeated once after a 30 s interval. The first video was of visual white noise and participants were instructed to passively observe the video. This was identified as the Baseline condition and served as a mu activation level baseline. The second video was of simple bouncing balls and the observer was again asked to passively observe the video (Ball condition). The third video was of a moving hand (Observation condition). The forth video was of the same moving hand and participants also imagined executing the observed hand movement (Imagination condition). As hypothesized, the Imagination condition activated the greatest level of mu suppression, while the Ball condition activated the lowest level of mu wave suppression. The Observation condition produced a slightly larger level of mu wave suppression than the Ball condition. This progressive increase in mu wave suppression supports the hypothesis that the activation of the mirror neuron system increases as the level of active observation increases.

Route of feeding influences the production and expression of tumor necrosis factor alpha in burned rats.

The effect of nutritional route on tumor necrosis factor alpha (TNF-alpha) production in burned rats was examined. Scald burns covering about 30% of the whole body surface area were inflicted on 43 male Wistar rats weighing about 200g. The animals were divided into three groups: CHOW (n = 10), total parenteral nutrition (TPN) (n = 22), and total enteral nutrition (TEN) (n = 11), continuously given a chow diet, TPN solution, or an enteral diet, respectively, for 7 days after the burn injury. The rate of detection of TNF-alpha in plasma on day 7 was significantly higher in the TPN group than in the CHOW or TEN groups. The messenger RNA (mRNA) expression of TNF-alpha was significantly increased in the spleen, lungs, liver, and ileum of the rats receiving TPN compared with the CHOW and TEN rats. On the other hand, the expression of TNF-alpha mRNA was markedly decreased in the thymus of the TPN group compared with the CHOW group. The mortality rate in the TPN group (63.6%) was higher than that in the CHOW (0.0%) or TEN (27.3%) groups on day 7 after burn injury. These data suggest that TPN increases the expression of TNF-alpha mRNA in organ tissues and systemic TNF-alpha production, and reduces the survival rate of rats after thermal injury, but TEN does not.

Expression of Bax and apoptosis-related proteins in human esophageal squamous cell carcinoma including dysplasia.

The rate of tumor growth depends on the balance between proliferation and death of tumor cells. It is known that Bax, caspase-3, and p53 proteins are death-promoting factors, whereas Bcl-2 protein is a death antagonist. We immunohistochemically examined the expression of Bax and apoptosis-related proteins such as caspase-3, p53, and Bcl-2 in 76 patients with human esophageal squamous cell carcinoma (SCC) including dysplasia to determine the relationship of expression of each protein to tumor behavior and patients' prognosis. No significant relationships in immunopositivity were found among these proteins in SCCs. Cytoplasmic Bax expression was exhibited in 63 cases of SCCs (82.9%). The apoptotic index of caspase-3-positive lesions was significantly higher than that of caspase-3-negative lesions in both dysplasia and SCC (P =.016, P =.012). On the other hand, the apoptotic index (1.18%) was significantly correlated with Bax overexpression in dysplasia (P =.006), but not in SCC lesions (P =.129). The patients with Bax-positive SCCs were found to have a poor prognosis by the Kaplan-Meier method (P =.043). These findings suggested that Bax expressed in dysplasia may play a role as an apoptotic factor, but that it may be functionally inactive in some cancerous lesions and thus not contribute to suppression of the tumor progression in some cases of human esophageal SCCs.

Coordination of Lewis acid to eta(2)-enonepalladium(0) leading to continuous structure variation from eta(2)-olefin type to eta(3)-allyl type.

The reaction of alpha,beta-unsaturated carbonyl compounds, a palladium(0) complex, and Lewis acids led to the formation of a new class of complexes showing a wide variety of structures with eta(2)-type and eta(3)-type coordination of the carbonyl compounds. The reaction of Pd(PhCH=CHCOCH(3))(PPh(3))(2) with BF(3).OEt(2) or B(C(6)F(5))(3) quantitatively gave palladium complexes 1a,b having BX(3)-coordinated eta(2)-enonepalladium structure, as revealed by X-ray structure analysis of the B(C(6)F(5))(3) adduct 1b. On the other hand, the reaction of Pd(PhCH=CHCHO)(PPh(3))(2) with BF(3).OEt(2) or B(C(6)F(5))(3) gave distorted zwitterionic eta(3)-allylpalladium complexes 3a,b, where the Pd-carbonyl carbon distance in 3a (2.413(4) A) is much shorter than that (2.96(1) A) in 1b. The values of the P-P coupling constant and (13)C chemical shift for carbonyl carbon are useful criteria for predicting how the eta(3)-coordination mode contributes to the structure of the enone-palladium-Lewis acid system. Molecular orbital calculations on the series of model complexes suggest that orbital overlap in the highest occupied molecular orbital between the palladium and carbonyl carbon is enlarged by coordination of the Lewis acid to the carbonyl group. Palladium-catalyzed conjugate addition of R-M (R-M = AlMe(3), AlEt(3), ZnEt(2)) and its plausible reaction path are also reported.

Carbon-carbon bond formation by electrophilic addition at the central carbon of the mu-eta(3)-allenyl/propargyl ligand on the Pd-Pd bond.

The mu-eta(3)-allenyl/propargyldipalladium complexes were synthesized by the reaction of the corresponding eta(1)-allenyl- or eta(1)-propargylpalladium complexes with Pd(2)(dba)(3). The X-ray diffraction analysis indicates that the dinuclear complex has a unique structure, in which two palladium, three carbon, two phosphorus, and one halogen atoms are in the same plane. These dinuclear complexes react with electrophiles, such as HCl or AcCl, at the central carbon of the mu-eta(3)-allenyl/propargyl ligand to give the mu-eta(3)-vinylcarbenedipalladium complexes. Intramolecular reaction proceeded smoothly to give cyclization products quantitatively. Addition of a catalytic amount of a palladium(0) complex dramatically accelerated the carbon-carbon bond formation. The MO calculations on the mu-eta(3)-allenyl/propargyl complexes indicated that the reaction proceeds via orbital control.

Long-term graft acceptance in rat heart transplantation by CTLA4Ig gene transfection combined with FTY720 treatment.

CTLA4Ig strongly adheres to B7 molecules on antigen-presenting cells to block intracellular signal transduction via CD28 on helper T cells, which eventually inhibits immune responses. We have demonstrated that the administration to recipient animals of adenoviral vectors containing CTLA4Ig gene (adCTLA4Ig) prolonged graft survival, although the gene expression diminished in a time-dependent manner and the grafts were finally rejected. In addition, recipient animals treated with FTY720, a new immunosuppressant, exhibited a decrease in the number of peripheral lymphocytes due to apoptosis. In this study, we performed adCTLA4Ig transfection combined with FTY720 treatment in heart-grafted rats to determine if the combination could induce a mutual effect on graft survival. The recipient animals were given injections of 1 x 10(9) plaque-forming units of adCTLA4Ig via the tail vein immediately after grafting. On the day before transplantation we administered FTY720 orally to some of these animals at a dosage of 5 mg/kg and again on the day of transplantation. The median graft survival period in the adCTLA4Ig-only group was 27 days, whereas that in the combination group was markedly prolonged to 56 days. Of 15 grafts, 5 survived indefinitely. In these groups we observed detectable levels of CTLA4Ig in the sera 49 days after grafting; the levels were always higher in the combination group than in the adCTLA4Ig-only group. As a result, this study revealed that FTY720 and adCTLA4Ig have a potent mutual effect on graft survival during rat heart transplantation. Furthermore, it is highly possible that FTY720 enhances gene expression of adCTLA4Ig, which may be related to the long-term acceptance of grafts.

Immunohistochemical characterization of p57KIP2 expression in human esophageal squamous cell carcinoma.

Functional defects in the CIP/KIP family of cyclin-dependent kinase inhibitors (CDKIs) have been shown to be associated with human malignancies. We immunohistochemically examined p57KIP2 (p57) expression in 92 patients with human esophageal squamous cell carcinoma (SCC) to determine the relationship between this expression and those of cyclin D1 and E. The p57 labeling index (LI) (defined as the percentage of p57-positive cells) in esophageal SCC was 43.3 +/- 3.2% (mean +/- standard error of the mean). In non-neoplastic esophageal epithelium, p57 staining was more frequently observed in the basal and parabasal cells than in surface layer cells. Immunostaining for cyclin D1 and E was observed in 28.2% (28/92) and 32.6% (30/92) of tumors, respectively. The median p57 LI in cyclin D1-positive cases was 66.2, and significantly higher than that in negative cases (31.9%) (p = 0.0009). There was no significant relationship between p57 LI and cyclin E expression (p = 0.147). As determined using Kaplan-Meier's method, loss of p57 immunoreactivity was not a prognostic factor for esophageal SCC (p = 0.548). Our in vivo findings suggested that p57 protein expression was positively correlated with cyclin D1 expression and that loss of p57 protein expression alone does not affect progression of esophageal SCC.