Monochromatic x-ray computed tomography (CT) at two different energies provides information about electron density of human tissue without ambiguity due to the beam hardening effect. This information makes the treatment planning for proton and heavy-ion radiotherapy more precise. We have started a feasibility study on dual energy x-ray CT by using synchrotron radiation. A translation-rotation scanning CT system was developed for quantitative measurement in order to clarify what precision in the measurement was achieved. Liquid samples of solutions of K2HPO4 and solid samples of tissue equivalent materials were used to simulate human tissue. The experiments were carried out using monochromatic x-rays with energies of 40, 70 and 80 keV produced by monochromatizing synchrotron radiation. The solid samples were also measured in a complementary method using high-energy carbon beams to evaluate the electron densities. The measured electron densities were compared with the theoretical values or the values measured in the complementary method. It was found that these values were in agreement in 0.9% on average. Effective atomic numbers were obtained as well from dual-energy x-ray CT. The tomographic image based on each of the electron densities and the effective atomic number presents a different feature of the material, and its contrast drastically differs from that in a conventional CT image.
Although there are several hypotheses explaining the mechanisms of immune-privileged status of malignant tumor, the exact pathway has yet to be explored. Cyclooxygenase (COX)-2 plays a vital role in prognosis of cancer patients in terms of contribution to neoangiogenesis and apoptosis inhibition; however, the impact of COX-2 in immunomodulation has not been reported. We have evaluated the expression of COX-2 and its impact on infiltration of immune-competent cells into the tumor cell nest in endometrial carcinoma. Tissue specimens from 70 endometrial carcinoma patients who had undergone a curative resection were evaluated for COX-2 expression and host immune status (CD8 ؉ T cells). COX-2 expression was associated with FIGO stage and myometrial invasion, but there was no statistically significant impact. CD8 ؉ T cells within cancer cell nest (Nest CD8) were inversely correlated with the expression level of COX-2 (p ؍ 0.0006). Nest CD8 became an independent predictor of patient survival (Hazard ratio ؍ 10.300, p ؍ 0.0304) in Cox's multivariate analysis. The expression level of COX-2 was found to be a significant predictor of disease relapse in univariate analysis (p ؍ 0.0294) but not in multivariate analysis (p ؍ 0.5949). In conclusion, increased nest CD8 produced a survival advantage in endometrial carcinoma patients. Moreover, tumor-produced COX-2, which reduces the infiltration of CD8 ؉ T cells into cancer cell nests, may allow tumors to avoid immune surveillance.
Active cancer treatment probably induces the symptoms related to infection and the use of anti-infective drugs. Unnecessary and excessive treatment should be avoided, and the symptoms should be managed with consideration of the patient's state of mind in order to improve the quality of life of terminally ill patients.
The effect of three plant lectins, soybean lectin (SBA), Japanese jack bean lectin (CGA), and wheat germ lectin (WGA), on the transport of various food factors, such as isoflavones, quercetin, dipeptides, and calcium ions, were investigated by use of an intestinal tract model, Caco-2 cell monolayers. The lectins increased the isoflavone transport but had no effect on aglycon transport. SBA increased the transport of quercetin glycosides, whereas CGA and WGA had no effect. The lectins increased the transport of calcium ions but showed no effect on the transport of dipeptides, carnosine, and anserine. Although SBA did not change the transepithelial electrical resistance (TER) value of the Caco-2 cell monolayers, CGA and WGA decreased the TER value. These results indicate that plant lectins affect the transport of food factors in different manners, presumably due to their specific sugar binding activity.
A multislit collimator was designed and fabricated for basic studies on microbeam radiation therapy (MRT) with an x-ray energy of about 100 keV. It consists of 30 slits that are 25 microm high, 30 mm wide, and 5 mm thick in the beam direction. The slits were made of 25 microm-thick polyimide sheets that were separated by 175 microm-thick tungsten sheets. The authors measured the dose distribution of a single microbeam with a mean energy of 125 keV by a scanning slit method using a phosphor coupled to a charge coupled device camera and found that the ratios of the dose at the center of a microbeam to that at midpositions to adjacent slits were 1050 and 760 for each side of the microbeam. This dose distribution was well reproduced by the Monte Carlo simulation code PHITS.
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