[Basic Knowledge of Neutron: Physics]

Neutrons are uncharged particles and exhibit strong ability to penetrate matter. Various charged particles and gamma rays are emitted from nuclear reactions induced by neutrons passing through the matter. It is important to consider contributions of neutrons for estimating such quantities used in radiation protection as absorbed dose, equivalent dose and effective dose. In this article basic knowledge of neutron is briefly summarized concerned with physical properties of neutrons, neutron reactions, neutron sources, fluence to karma conversion coefficient, absorbed dose, equivalent dose, effective dose.

Development and characterization of optical readout well-type glass gas electron multiplier for dose imaging in clinical carbon beams

The use of carbon ion beams in cancer therapy (also known as hadron therapy) is steadily growing worldwide; therefore, the demand for more efficient dosimetry systems is also increasing because daily quality assurance (QA) measurements of hadron radiotherapy is one of the most complex and time consuming tasks. The aim of this study is to develop a two-dimensional dosimetry system that offers high spatial resolution, a large field of view, quick data response, and a linear dose-response relationship. We demonstrate the dose imaging performance of a novel digital dose imager using carbon ion beams for hadron therapy. The dose imager is based on a newly-developed gaseous detector, a well-type glass gas electron multiplier. The imager is successfully operated in a hadron therapy facility with clinical intensity beams for radiotherapy. It features a high spatial resolution of less than 1 mm and an almost linear dose-response relationship with no saturation and very low linear-energy-transfer dependence. Experimental results show that the dose imager has the potential to improve dosimetry accuracy for daily QA.

Energy of the ^{229}Th Nuclear Clock Isomer Determined by Absolute γ-ray Energy Difference

The low-lying isomeric state of ^{229}Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by taking the absolute energy difference between the excitation energy required to populate the 29.2-keV state from the ground state and the energy emitted in its decay to the isomeric excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV γ ray. Together with the cross-band transition energy (29.2  keV→ground) and the branching ratio of the 29.2-keV state measured in a recent study, the isomer energy was determined to be 8.30±0.92  eV. Our result is in agreement with the latest measurements based on different experimental techniques, which further confirms that the isomeric state of ^{229}Th is in the laser-accessible vacuum ultraviolet range.

Development of a microcalorimeter with transition edge sensor for detection of LX rays emitted by transuranium elements

A transition edge sensor (TES) microcalorimeter has been developed for use as an energy dispersive X-ray spectrometer. The TES microcalorimeter is a thermal detector that enables one to determine the energy of an incident photon by measuring the resultant increase in temperature. In this work, a Ti/Au TES microcalorimeter was developed to measure LX rays emitted by transuranium elements. The phase transition temperature was set at ~200 mK by using a bilayer structure composed of a 110-nm-thick Au layer and a 40-nm-thick Ti layer. An Au of 5 µm thickness was deposited on the Ti/Au bilayer to achieve an absorption efficiency of 35-80 % for the energy range of LX rays (10-25 keV). The developed TES microcalorimeter was irradiated with LX rays emitted by an (241)Am source at an operating temperature of 140 mK. An energy resolution of ~80 eV (full width at the half maximum) was obtained for L(β1)X ray of 17.75 keV.

Microcalorimeter-type energy dispersive X-ray spectrometer for a transmission electron microscope

A new energy dispersive X-ray spectrometer (EDS) with a microcalorimeter detector equipped with a transmission electron microscope (TEM) has been developed for high- accuracy compositional analysis in the nanoscale. A superconducting transition-edge-sensor-type microcalorimeter is applied as the detector. A cryogen-free cooling system, which consists of a mechanical and a dilution refrigerator, is selected to achieve long-term temperature stability. In order to mount these detector and refrigerators on a TEM, the cooling system is specially designed such that these two refrigerators are separated. Also, the detector position and arrangement are carefully designed to avoid adverse affects between the superconductor detector and the TEM lens system. Using the developed EDS system, at present, an energy resolution of 21.92 eV full-width-at-half maximum has been achieved at the Cr K alpha line. This value is about seven times better than that of the current typical commercial Si(Li) detector, which is usually around 140 eV. The developed microcalorimeter EDS system can measure a wide energy range, 1-20 keV, at one time with this high energy resolution that can resolve peaks from most of the elements. Although several further developments will be needed to enable practical use, highly accurate compositional analysis with high energy resolution will be realized by this microcalorimeter EDS system.

Is the adjustment of serum creatinine level < 0.6 mg/dl to 0.6 mg/dl justified in estimates of carboplatin clearance calculated by the Jelliffe formula?

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Background: The Jelliffe formula (JF) does not include body surface area (BSA) or body weight to adjust the body size. We demonstrated that estimates of carboplatin clearance calculated by the JF tend to have greater positive bias compared to other formulae. The JF has been used to estimate carboplatin clearance in Gynecologin Oncology Group studies. In patients with serum creatinine level <0.6 mg/dl, it is adjusted to 0.6 mg/dl in estimates of carboplatin clearance (Adjusted-Jelliffe formula (AJF)). The purpose of this study is to evaluate whether this adjustment is suitable. Methods: Carboplatin clearance was estimated in 115 patients with serum creatinine <0.6 mg/dl who received carboplatin-based chemotherapy for gynecologic malignancies between January 1996 and August 2004. Creatinine clearance was estimated using the Cockroft-Gault formula (CGF), JF, and AJF. The median percent error (MPE) and the median absolute percent error (MAPE) were evaluated by comparing carboplatin clearance. The relationships between BSA and ratios of estimated carboplatin clearance (JF/CGF, AJF/CGF) were evaluated by using simple regression. Results: The estimated carboplatin clearances were: CGF, 126.7 ± 27.7; JF, 148.2 ± 20.5; AJF, 130.5 ± 14.3. Comparing the results of the CGF with the JF, AJF yielded MPEs of +20%, +6%, and MAPEs of 21%, 14%, respectively. There were the linear correlations between ratio of estimated carboplatin clearances and BSA (Y1 = −1.141X + 2.830, Y2 = -1.061 X + 2.581, Y1: ratio of carboplatin clearance (JF/CGF), Y2: ratio of carboplatin clearance (AJF/CGF), X: BSA). Conclusions: As expected, carboplatin clearance was decreased by adjusting serum creatinine to 0.6 mg/ml, but it did not adjust the bias by BSA. Estimates of carboplatin clearance calculated by the AJF tend to have greater negative bias, particularly when the BSA of the patient is large.

No significant financial relationships to disclose.

Paclitaxel inhibits expression of heat shock protein 27 in ovarian and uterine cancer cells

The purpose of the study was to determine whether paclitaxel inhibits the expression of heat shock protein 27 (HSP27) in two gynecologic cancer cell lines compared with other antineoplastic agents having different cytotoxic mechanisms. BG-1 ovarian cancer cells and HeLa uterine cancer cells were treated with a tubulin depolymerization inhibitor (paclitaxel), a topoisomerase-II inhibitor (etoposide), and two tubulin polymerization inhibitors (colcemid and vincristine). Cell kills were evaluated by counting the number of cells. Propidium iodide staining and flow cytometric analysis were applied for the determination of cell-cycle perturbation. HSP27 was stained by the indirect immunofluorescence technique and analyzed with a flow cytometer. In both BG-1 and HeLa cells, growth arrest and G2 / M accumulation were dependent on the dose of each cytotoxic agent. There were positive correlations between HSP27 overexpression and growth arrest and G2 / M accumulation when the cell lines were treated with etoposide, colcemid, or vincristine, but not with paclitaxel. Paclitaxel completely inhibited the expression of HSP27. The results of this study indicated that paclitaxel may possess unique mechanisms able to overcome drug resistance by inhibiting HSP27 expression.

Paclitaxel inhibits expression of heat shock protein 27 in ovarian and uterine cancer cells

The purpose of the study was to determine whether paclitaxel inhibits the expression of heat shock protein 27 (HSP27) in two gynecologic cancer cell lines compared with other antineoplastic agents having different cytotoxic mechanisms. BG-1 ovarian cancer cells and HeLa uterine cancer cells were treated with a tubulin depolymerization inhibitor (paclitaxel), a topoisomerase-II inhibitor (etoposide), and two tubulin polymerization inhibitors (colcemid and vincristine). Cell kills were evaluated by counting the number of cells. Propidium iodide staining and flow cytometric analysis were applied for the determination of cell-cycle perturbation. HSP27 was stained by the indirect immunofluorescence technique and analyzed with a flow cytometer. In both BG-1 and HeLa cells, growth arrest and G2/M accumulation were dependent on the dose of each cytotoxic agent. There were positive correlations between HSP27 overexpression and growth arrest and G2/M accumulation when the cell lines were treated with etoposide, colcemid, or vincristine, but not with paclitaxel. Paclitaxel completely inhibited the expression of HSP27. The results of this study indicated that paclitaxel may possess unique mechanisms able to overcome drug resistance by inhibiting HSP27 expression.

Endocervical adenomyoma. A case report with histochemical and immunohistochemical studies

We report a case of adenomyoma of endocervical type arising in a 44-year-old female. Grossly, a well-circumscribed tumor protruding from the right side of the uterine cervix was seen which was assumed to be an ovarian tumor by imaging studies carried out preoperatively. The tumor was composed of a mixture of proliferating glands of endocervical type and fascicles of smooth muscle cells. There was no distinct nuclear anaplasia in the proliferating glands, there were no architectural abnormalities, and there was no evidence of destructive stromal invasion such as desmoplasia. Minimal deviation adenocarcinoma, which shows a gastric phenotype with immunoreactivity for M-GGMC-1 and predominantly PAS-positive neutral mucin, was a serious diagnostic possibility, but the lesion was well-circumscribed, cytologic and architectural abnormalities were absent, and staining for M-GGMC-1 was negative, which suggested a diagnosis of endocervical adenomyoma. An increased Ki-67 labeling index by up to 20%, the presence of predominantly PAS-positive neutral mucin, and membranous immunoreactivity for CEA in limited areas were diagnostic pitfalls, which could lead to an erroneous diagnosis of minimal deviation adenocarcinoma of the uterine cervix. Therefore, the results of these ancillary techniques should be interpreted with caution and combined with gross and light microscopic features.

Isoaurostatin, a novel topoisomerase inhibitor produced by Thermomonospora alba

A novel inhibitor of topoisomerase I designated as isoaurostatin (1) was isolated from the culture filtrate of Thermomonospora alba strain No. 1520. The structure of 1 was determined to be 6,4'-dihydroxyisoaurone on the basis of spectroscopic (NMR and MS) methods. Compound 1 inhibited the relaxation activity of calf thymus topoisomerase I in a noncompetitive manner and did not inhibit the relaxation and decatenation of human placenta topoisomerase II. Compound 1 is an inhibitor belonging to cleavable complex-nonforming type without DNA intercalation.

[A case of clear cell carcinoma of the ovary responding to a paclitaxel-carboplatin combination chemotherapy]

Clear cell carcinoma of the ovary is believed to be chemoresistant; therefore, choosing anticancer agents is often difficult. In this report we present a case of ovarian clear cell carcinoma that showed a significant response to a combination chemotherapy with paclitaxel and carboplatin. The patient is a 51-year-old Japanese female with a history of Gn-RH treatment for endometriosis that was terminated three years before the presentation of this disease. She was referred to our hospital because of a huge abdominal mass. The initial surgery revealed the tumor was a clear cell carcinoma of the left ovary, showing a predominantly solid growth pattern as well as papillary and tubular patterns. Both architectural and nuclear grades were interpreted as 3, and mitotic count was up to 5/10 high-power fields. Therefore, the tumor was considered to be grade 2. A huge para-aortic lymph node metastasis was not resectable. Combination chemotherapy using paclitaxel at 175 mg/m2 in 3 hr intravenous infusion followed by intraperitoneal infusion of carboplatin at AUC of 7.5 as a bolus was administered. The regression rate of the para-aortic lymph node metastasis was 85%, lasting more than 5 months. We believe that the combination of paclitaxel and carboplatin is one treatment choice for clear cell carcinoma of the ovary.