Search Results (4)

The generation of highly charged ions in laser plasmas is usually associated with collisional ionization processes that occur in electron–ion collisions. An alternative ionization channel caused by tunnel ionization in an optical field is also capable of effectively producing highly charged ions with ionization potentials of several kiloelectronvolts when the laser intensity q > 10²⁰ W/cm². It is challenging to clearly distinguish the impacts of the optical field and collisional ionizations on the evolution of the charge state of a nonequilibrium plasma produced by the interaction of high-intensity, ultrashort PW-class laser pulses with dense matter. In the present work, it is shown that the answer to this question can be obtained in some cases by observing the X-ray spectral lines caused by the transition of an electron into the K-shell of highly charged ions. The time-dependent calculations of plasma kinetics show that this is possible, for example, if sufficiently small clusters targets with low-density background gas are irradiated. In the case of Ar plasma, the limit of the cluster radius was estimated to be R₀ = 0.1 μm. The calculation results for argon ions were compared with the results of the experiment at the J-KAREN-P laser facility at QST-KPSI. Full article

Pancreatic cancer (PC) is one of the most fatal cancers, and there is an urgent need to develop new anticancer agents with fewer side effects for the treatment of this condition. A patient-derived xenograft (PDX) mouse model transplanted with cancer tissue from patients is widely accepted as the best preclinical model for evaluating the anticancer potential of drug candidates. Fucoxanthin (Fx) is a highly polar carotenoid contained in edible marine brown algae and possesses anticancer activity. However, there is a lack of data on the effects of Fx in PDX models. We investigated the anticancer effects of Fx in PDX mice transplanted with cancer tissues derived from a patient with PC (PC-PDX) using comprehensive protein expression assay. Fx administration (0.3%Fx diet) ad libitum for 27 days significantly abrogated tumor development (0.4-fold) and induced tumor differentiation in PC-PDX mice, as compared to those in the control mice. Fx significantly upregulated the expression of non-glycanated DCN (2.4-fold), tended to increase the expressions of p-p38(Thr¹⁸⁰/Tyr¹⁸²) (1.6-fold) and pJNK(Thr¹⁸³/Tyr¹⁸⁵) (1.8-fold), significantly downregulated IGFBP2 (0.6-fold) and EpCAM (0.7-fold), and tended to decrease LCN2 (0.6-fold) levels in the tumors of the PC-PDX mice, as compared to those in the control mice. Some of the protein expression patterns were consistent with the in vitro experiments. That is, treatment of fucoxanthinol (FxOH), a prime metabolite derived from dietary Fx, enhanced non-glycanated DCN, p-p38(Thr¹⁸⁰/Tyr¹⁸²), and pJNK(Thr¹⁸³/Tyr¹⁸⁵) levels in human PC PANC-1 and BxPC-3 cells.These results suggested that Fx exerts anticancer and differentiation effects in a PC-PDX mice through alterations of some multifunctional molecules. Full article

Nuclear reactions between protons and boron-11 nuclei (p–B fusion) that were used to yield energetic α-particles were initiated in a plasma that was generated by the interaction between a PW-class laser operating at relativistic intensities (~3 × 10¹⁹ W/cm²) and a 0.2-mm thick boron nitride (BN) target. A high p–B fusion reaction rate and hence, a large α-particle flux was generated and measured, thanks to a proton stream accelerated at the target’s front surface. This was the first proof of principle experiment to demonstrate the efficient generation of α-particles (~10¹⁰/sr) through p–B fusion reactions using a PW-class laser in the “in-target” geometry. Full article

Although epidemiological studies have shown a relationship between periodontal disease and pancreatic cancer, the molecular mechanisms involved remain unclear. In this study, the effects of systemic administration of Porphyromonas gingivalis lipopolysaccharide (PG-LPS) on gene expression were comprehensively explored in mouse pancreas that did not demonstrate any signs of inflammation. PG-LPS was prepared in physiological saline and intraperitoneally administered to male mice at a concentration of 5 mg/kg every 3 days for 1 month. After extracting total RNA from the excised mice pancreas, a comprehensive DNA microarray analysis of gene expression was performed. Tissue specimens were also subjected to hematoxylin–eosin staining and immunohistochemistry using anti-regenerating islet-derived 3A and G (Reg3A/G) antibody. ImageJ software was used to quantify the area of Reg3A/G positive cells in pancreatic islets by binarizing image date followed by area extraction. The results were compared using Mann–Whitney U test. Data are presented as mean ± standard deviation (SD) with p < 0.05 considered as significant. Reg3G, a gene related to pancreatic cancer, was one of the 10 genes with the highest levels of expression in the pancreas stimulated with PG-LPS. The comprehensive analysis revealed a 73-fold increase in Reg3G expression level in the PG-LPS group when compared with the control group; in addition, the expression level of Reg3A was increased by 11-fold in the PG-LPS group. Image analysis showed that the ratio of Reg3A/G positive cells was higher in the PG-LPS group than the control. Immunostaining showed the presence of Reg3A/G-positive cells in the alpha-cell equivalent areas around the islets of Langerhans in the PG-LPS group. These results support the notion that periodontal disease may be a risk factor for pancreatic cancer. Full article