According to cancer genome sequences, more than 90% of cases of pancreatic ductal adenocarcinoma (PDAC) harbor active KRAS mutations. Digital PCR (dPCR) enables accurate detection and quantification of rare mutations. We assessed the dynamics of circulating tumor DNA (ct‐DNA) in patients with advanced PDAC undergoing chemotherapy using dPCR. KRAS G12/13 mutation was assayed by dPCR in 47 paired tissue‐ and ct‐DNA samples. The 21 patients were subjected to quantitative ct‐DNA monitoring at 4 to 8‐week intervals during chemotherapy. KRAS mutation was detected in 45 of those 47 patients using tissue DNA. In the KRAS mutation‐negative cases, next‐generation sequencing revealed KRAS Q61K and NRAS Q61R mutations. KRAS mutation was detected in 23/45 cases using ct‐DNA (liver or lung metastasis, 18/19; mutation allele frequency [MAF], 0.1%‐31.7%; peritoneal metastasis, 3/9 [0.1%], locally advanced, 2/17 [0.1%‐0.2%]). In the ct‐DNA monitoring, the MAF value changed in concordance with the disease state. In the 6 locally advanced cases, KRAS mutation appeared concurrently with liver metastasis. Among the 6 cases with liver metastasis, KRAS mutation disappeared during the duration of stable disease or a partial response, and reappeared at the time of progressive disease. The median progression‐free survival was longer in cases in which KRAS mutation disappeared after an initial course of chemotherapy than in those in which it was continuously detected (248.5 vs 50 days, P < .001). Therefore, ct‐DNA monitoring enables continuous assessment of disease state and could have prognostic utility during chemotherapy.

Fas, a member of the tumor necrosis factor receptor/nerve growth factor receptor family, induces apoptosis by crosslinking with Fas ligand or anti‐Fas antibody in a variety of cultured cells. We examined the expression of Fas antigen and its mediation of apoptosis in six human gastric carcinoma cell lines. Flow cytometric analysis and western blotting revealed relatively high expression of Fas antigen in MKN‐74 (wild‐type p53 gene) and MKN‐45 (wild‐type), followed by MKN‐1 (mutated), MKN‐7 (mutated) and KATO‐III (deleted). MKN‐28 (mutated) showed minimal expression of the antigen. The expression was apparently enhanced by interferon‐γ, except for MKN‐1 and MKN‐28. Anti‐Fas antibody (100 ng/ml) induced nuclear fragmentation characteristic of apoptosis. Apoptosis occurred in a delayed fashion and the apoptotic index at 72 h was approximately 60% in MKN‐74, 35% in MKN‐45, and 20% in MKN‐1 and KATO‐III. A DNA ladder was noted in MKN‐74 at 72 h. Expression levels of P53 and P21Wafl did not change for up to 48 h in MKN‐74. The biological effects did not correlate with endogenous Bcl‐2 expression. These results indicated that a) Fas antigen is variably expressed in human cultured gastric carcinoma cells, b) the protein transduces an apoptotic signal which leads to delayed cell death, and c) susceptibility to the antibody correlates well with the expression level of Fas antigen.

To survey the estrogenic activity of the organic extracts from particulate matter of urban ambient outdoor air, samples were collected on glass fiber filters using a high-volume air sampler on the rooftop of our institute for 6 months (six filters/month). After extracting the organic materials and separating them into three fractions, i.e., acidic, neutral, and basic, we applied a cell-growth assay using MCF-7 human breast cancer cells to the original extract and the extracts of the fractions. Only the extract in the acidic fraction showed cell proliferation activity in a dose-response manner. To survey the chemical(s) responsible for the activity, a gas chromatography/mass spectrometry (GC/MS) analysis was conducted after silylating the extract. The presence of bisphenol A (BPA) was confirmed, because the retention times and the MS fragment patterns between the silylated derivative of a component in the sample and that of BPA itself were the same. By using a GC/MS-SIM (selective ion monitoring) technique, the average value was found to be 0.51 ng/m(3) of air (range: 0.02 approximately 1.92 ng/m(3) of air). The trend of the residual levels in air particulates showed seasonal variation, increasing from autumn to winter and decreasing from winter to spring. The only exception was that the value in January was lower than those in December and February. Considering the content of BPA in the extract of the acidic fraction and the strength of the activities with the extract and BPA itself, the estrogenic activity due to BPA in the fraction seemed to decrease. In spite of this decline, the possibility remains that the estrogenic activity mainly originated from BPA.

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Twenty-two cases of purely ocular myasthenia gravis were reviewed to evaluate the long-term effects of thymectomy. Remission rate increased gradually with time (11.8% at 3 years, 23.1% at 5 years, and 33.3% at 10 years). Analysis of factors influencing remission with time showed that patients with short duration of illness attained remission significantly earlier (p = 0.035 at 5-year follow-up). One of 22 patients with purely ocular myasthenia gravis (4.5%) had disease progression. Because ocular myasthenia gravis often progresses to the generalized type and because duration of illness before operation is one of important factors influencing remission, we conclude that thymectomy in the earlier stages of the disease is the preferred treatment for ocular myasthenia gravis, just as for generalized myasthenia gravis.