ObjectiveEarly detection and early treatment are of vital importance to the successful treatment of various cancers. The development of a novel screening method that is as economical and non-invasive as the faecal occult blood test (FOBT) for early detection of colorectal cancer (CRC) is needed. A study was undertaken using canine scent detection to determine whether odour material can become an effective tool in CRC screening.DesignExhaled breath and watery stool samples were obtained from patients with CRC and from healthy controls prior to colonoscopy. Each test group consisted of one sample from a patient with CRC and four control samples from volunteers without cancer. These five samples were randomly and separately placed into five boxes. A Labrador retriever specially trained in scent detection of cancer and a handler cooperated in the tests. The dog first smelled a standard breath sample from a patient with CRC, then smelled each sample station and sat down in front of the station in which a cancer scent was detected.Results33 and 37 groups of breath and watery stool samples, respectively, were tested. Among patients with CRC and controls, the sensitivity of canine scent detection of breath samples compared with conventional diagnosis by colonoscopy was 0.91 and the specificity was 0.99. The sensitivity of canine scent detection of stool samples was 0.97 and the specificity was 0.99. The accuracy of canine scent detection was high even for early cancer. Canine scent detection was not confounded by current smoking, benign colorectal disease or inflammatory disease.ConclusionsThis study shows that a specific cancer scent does indeed exist and that cancer-specific chemical compounds may be circulating throughout the body. These odour materials may become effective tools in CRC screening. In the future, studies designed to identify cancer-specific volatile organic compounds will be important for the development of new methods for early detection of CRC.
Thermodynamics of scalar fields is investigated in three dimensional black hole backgrounds in two approaches. One is mode expansion and direct computation of the partition sum, and the other is the Euclidean path integral approach. We obtain a number of exact results, for example, mode functions, Hartle-Hawking Green functions on the black holes, Green functions on a cone geometry, free energies and entropies. They constitute reliable bases for the thermodynamics of scalar fields. It is shown that thermodynamic quantities largely depend upon the approach to calculate them, boundary conditions for the scalar fields and regularization method. We find that, in general, the entropies are not proportional to the area of the horizon and that their divergent parts are not necessarily due to the existence of the horizon. †
We consider entanglement through permeable interfaces in the c = 1 (1+1)dimensional conformal field theory. We compute the partition functions with the interfaces inserted. By the replica trick, the entanglement entropy is obtained analytically.The entropy scales logarithmically with respect to the size of the system, similarly to the universal scaling of the ordinary entanglement entropy in (1+1)-dimensional conformal field theory. Its coefficient, however, is not constant but controlled by the permeability, the dependence on which is expressed through the dilogarithm function.The sub-leading term of the entropy counts the winding numbers, showing an analogy to the topological entanglement entropy which characterizes the topological order in (2+1)-dimensional systems.
9Biomolecular Engineering Research Institute (BERI), Japan O6-methylguanine-DNA methyltransferase (MGMT) repairs the cytotoxic and mutagenic O6-alkylguanine produced by alkylating agents such as chemotherapeutic agents and mutagens. Recent studies have shown that in a subset of tumors, MGMT expression is inversely linked to hypermethylation of the CpG island in the promoter region; however, how the epigenetic silencing mechanism works, as it relates to hypermethylation, was still unclear. To understand the mechanism, we examined the detailed methylation status of the whole island with bisulfitesequencing in 19 MGMT non-expressed cancer cell lines. We found two highly methylated regions in the island. One was upstream of exon 1, including minimal promoter, and the other was downstream, including enhancer. Reporter gene assay showed that methylation of both the upstream and downstream regions suppressed luciferase activity drastically. Chromatin immunoprecipitation assay revealed that histone H3 lysine 9 was hypermethylated throughout the island in the MGMT negative line, whereas acetylation on H3 and H4 and methylation on H3 lysine 4 were at significantly high levels outside the minimal promoter in the MGMT-expressed line. Furthermore, MeCP2 preferentially bound to the CpG-methylated island in the MGMT negative line. Given these results, we propose a model for gene silencing of MGMT that is dependent on the epigenetic state in cancer.
We investigate the string theory on three dimensional black holes discovered by Bañados, Teitelboim and Zanelli in the framework of conformal field theory. The model is described by an orbifold of the SL(2, R) WZW model. The spectrum is analyzed by solving the level matching condition and we obtain winding modes. We then study the ghost problem and show explicit examples of physical states with negative norms. We discuss the tachyon propagation and the target space geometry, which are irrelevant to the details of the spectrum. We find a self-dual T-duality transformation reversing the black hole mass. We also discuss difficulties in string theory on curved spacetime and possibilities to obtain a sensible string theory on three dimensional black holes. This work is the first attempt to quantize a string theory in a black hole background with an infinite number of propagating modes.
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