Candidate Resonant Tetraneutron State Populated by the ^{4}He(^{8}He,^{8}Be) Reaction

A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction ^{4}He(^{8}He,^{8}Be) at 186  MeV/u. The energy of the state is 0.83±0.65(stat)±1.25(syst)  MeV above the threshold of four-neutron decay with a significance level of 4.9σ. Utilizing the large positive Q value of the (^{8}He,^{8}Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

Nonquenched Isoscalar Spin-M1 Excitations in sd-Shell Nuclei

Differential cross sections of isoscalar and isovector spin-M1 (0(+)→1(+)) transitions are measured using high-energy-resolution proton inelastic scattering at E(p)=295  MeV on (24)Mg, (28)Si, (32)S, and (36)Ar at 0°-14°. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to E(x)=16  MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transitions, while the matrix elements for isovector spin-M1 transitions are quenched by an amount comparable with the analogous Gamow-Teller transitions on those target nuclei.

Histological changes in chronic autoimmune SKG-arthritis evaluated by quantitative three-dimensional stereological estimators

OBJECTIVES

To investigate the quantitative arthritic and bone erosive changes, including the number of osteoclasts and osteoclast precursors in the new SKG-model of inflammatory polyarthritis using three-dimensional (3D) stereological methods.

METHODS

Arthritis was induced in female SKG-mice with Zymosan A. Quantitative histology was made in four control mice and four mice with arthritis euthanised after 6 and 12 weeks. The right hind paw was embedded undecalcified in methylmethacrylate and cut exhaustively generating vertical uniform random sections. A computer controlled microscope and stereological software was used for histological quantification. Total volumes were estimated according to the Cavalieri principle, total surfaces were estimated using the vertical sections design, and the number of osteoclasts was counted in a physical fractionator.

RESULTS

The arthritis score increased during the 12-week period and was paralleled by an increase in the volume of inflammatory tissue (r=0.96, p<0.001). The number of osteoclasts on bone (r=0.77, p<0.05) and osteoclast-covered bone surface (r=0.62, p<0.05) increased resulting in a decrease in the volume of bone (r=-0.65, p<0.05). However, the number of osteoclast precursors declined between week 6 and 12 (p<0.05). Furthermore, the total cartilage surface (r=-0.74, p<0.05) and cartilage volume (r=-0.74, p<0.05) decreased during the 12 weeks of arthritis.

CONCLUSIONS

In this study we demonstrated changes in 3D stereological parameters of inflammatory tissue, bone erosion, osteoclasts, and cartilage in mouse paws during the course of arthritis in the SKG mouse. This is the first time 3D quantitative histology has been applied in a mouse model of rheumatoid arthritis.

Perturbations of both nonregulatory and regulatory FOXP3+ T cells in patients with malignant melanoma

BACKGROUND

'FOXP3+ regulatory T cells' (Tregs) are reported to be increased in tumour-bearing hosts including patients with melanoma, leading to tumour immune suppression. However, this idea is challenged by recent evidence that the 'FOXP3+ Treg' fraction in fact contains activated 'nonregulatory' T cells. Also, FOXP3+ T cells are reported to have functionally and kinetically distinct subsets.

OBJECTIVES

To investigate whether either or both of regulatory and 'nonregulatory' FOXP3+ T cells are perturbed in patients with melanoma.

METHODS

FOXP3+ T cells were classified into three subsets, namely CD45RO+FOXP3(low) nonregulatory T cells, CD45RO+FOXP3(high) effector Tregs, and CD45RO-FOXP3(low) naïve Tregs, according to their expression levels of FOXP3 and CD45RO. The percentage and cytokine production of these FOXP3+ T-cell subsets were assessed by flow cytometry.

RESULTS

Both regulatory and nonregulatory T cells were increased in patients with melanoma. Moreover, we found three unexpected perturbations in FOXP3+ T-cell subsets: (i) patients with melanoma showed higher frequencies of FOXP3(low) nonregulatory T cells, which decreased and normalized after tumour removal; (ii) FOXP3(low) naïve Tregs containing higher frequencies of interferon-γ+ cells increased with tumour progression; and (iii) CD45RO+FOXP3(high) effector Tregs were pronouncedly infiltrated around tumour tissues.

CONCLUSIONS

These findings demonstrate that patients with melanoma have distinct and differential perturbation of both regulatory and nonregulatory FOXP3+ T cells. The degree of perturbation is associated with tumour burden and progression, suggesting that the perturbation reflects fundamental pathophysiological processes in patients with melanoma. The presented analysis provides a practical approach to investigate the immunological environment of cancer patients.

Lineage admixture during postglacial range expansion is responsible for the increased gene diversity of Kalopanax septemlobus in a recently colonised territory

We aimed to reveal the effects of range expansion and subsequent lineage admixture from separated glacial refugia on genetic diversity of Kalopanax septemlobus in Japan, by combining nuclear microsatellite data and ecological niche modelling. Allelic richness and gene diversity were compared at the population and regional level. We also statistically examined these indices as a function of population accessibility to the last glacial maximum (LGM) palaeodistribution reconstructed by ecological niche modelling to test a simple range expansion scenario from glacial refugia. Genetic diversity was highest in the populations of southern Japan and gradually decreased towards the north. However, an additional centre of genetic diversity, when measured as gene diversity, was found in northern Honshu Island, where distinct lineages were shown to be in contact. Positive effects of population accessibility to the LGM range were detected in both diversity indices at different spatial scales. The combined data support independent postglacial range expansions towards the north from the edge populations on the exposed coastal shelf of Pacific and Sea of Japan in northern Honshu during the LGM, which subsequently resulted in markedly low genetic diversity in the northernmost extant range, Hokkaido. The regional increase in gene diversity in northern Honshu is likely to be the result of postglacial lineage admixture. Relative difference in the spatial scales best relating population genetic diversity with the LGM distribution can be explained by a higher rate of allelic richness diversity loss during range expansions and stronger effects of lineage admixture on gene diversity.