Masashi Furukawa

The role of dimer formation in the self-assemblies of DNA base molecules on Cu(111) surfaces: A scanning tunneling microscope study

For the purpose of understanding the self-assembly formation mechanism of DNA base molecules, guanine, adenine, cytosine, and thymine molecules were deposited on Cu(111) surfaces, and were observed using a low-temperature (≈80 K) scanning tunneling microscope (STM). Single-molecular-scale STM images revealed that guanine, adenine, and cytosine molecules can form ordered one- and/or two-dimensional unique structures, but thymine molecules, however, randomly aggregate into small clusters. Semiempirical molecular orbital (MO) calculation indicates that there exists predominantly stable dimer structures for the former three molecules, while such phenomena cannot be observed among the possible thymine dimer and even trimer structures. Based on experimental and theoretical results, we have concluded that specific hydrogen-bonded nucleus formation is a decisive process in the two-dimensional self-assembly formation of DNA base molecules on Cu(111) surfaces.

Geometrical characterization of pyrimidine base molecules adsorbed on Cu(1 1 0) surfaces: XPS and NEXAFS studies

The structures of pyrimidine base molecules of thymine and cytosine adsorbed onto Cu(110) surfaces (0 > 1.0 ML) have been discussed based on the results of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The NEXAFS analysis for azimuthal orientation of molecules on surfaces indicates that the adsorbed molecules are in an upright configuration with their n plane parallel to the row structure ([110] direction), well below saturation coverage (θ ∼ 0.2 ML). Based on the chemical shifts observed in XP spectra (N1s, O1s region), the molecules have been determined to interact with surfaces through their nitrogen atom (lone-pair) next to the carbonyl group (C=O).

Cytoplasmic and serum galectin-3 in diagnosis of thyroid malignancies

In order to address whether galectin-3 in the sera and fine needle aspirates serve as a diagnostic marker distinguishing between benign and malignant thyroid nodules, we developed an enzyme-linked immunosorbent assay. We quantified galectin-3 in fine needle aspirates from a series of 118 patients with thyroid nodules and serum galectin-3 from another series of 46 patients, which were compared with final histology after thyroidectomy. Relative galectin-3 value (ng/mg), defined as galectin-3 concentration (ng/ml) divided by total protein concentration (mg/ml) in fine needle aspirates, was significantly higher in papillary carcinoma than in the other thyroid entities. There was no significant difference in serum galectin-3 level among patients with thyroid nodules and healthy individuals. Accordingly, relative galectin-3 value allows a definitive diagnosis of papillary carcinoma independent of cellular morphology, whereas serum galectin-3 does not serve as a marker for papillary carcinoma.

Scanning tunneling microscopy observation of two-dimensional self-assembly formation of adenine molecules on Cu(111) surfaces

Abstract The mechanism of self-assembly formation of adenine, one of the DNA base molecules, on atomically flat Cu(111) surfaces has been studied with scanning tunneling microscopy (STM). The observed STM images have shown that the formation of characteristic self-assembled structures depends not only on the coverage of the molecules but also on the deposition rate (intensity of the flux). We have observed ‘disordered one-dimensional chains’ for large coverage and high deposition rate, ‘disordered one-dimensional chains’ and ‘hexagonal structures’ for large coverage and moderate deposition rate, and ‘hexagonal structures’ and ‘parallel one-dimensional chains’ for low coverage and low deposition rates. We have proposed structure models for these self-assemblies in which each adenine molecule is connected to its neighbors by hydrogen bonds. The observed dependence of the self-assembled structure on both the coverage and the deposition rate indicates that a dynamic process at the surface plays an important role in its formation.

Psychological condition in patients with intractable Meniere's disease

Abstract Conclusions: Physicians should consider additional treatment strategies for Menieres disease patients with a long history of disease and hearing loss in the secondary affected ear and also provide psychological support regarding future progressive bilateral hearing loss. Objectives: To treat intractable Menieres disease patients effectively, we need to understand the psychological condition of each patient. We examined the state of neurosis and depression in patients and correlated this with demographic and background information. Methods: Between 1998 and 2009, we enrolled 207 patients with intractable Menieres disease in this prospective study. We used the Cornell Medical Index and the Self-rating Depression Scale to evaluate their psychological condition. We also obtained demographic and background information relating to sex, age, duration of disease, vertigo frequency, hearing level in bilateral sides, and plasma vasopressin level. Results: Neurosis and depression was diagnosed in 40.1% and 60.4%, respectively, of patients with intractable Menieres disease. Our results showed that surgical treatment significantly improved vertigo and hearing ability in patients with no psychological symptoms compared with those exhibiting psychological symptoms. Patients with a longer duration and worse hearing level in the secondary affected ear had a significantly higher incidence of mental illness than those with a shorter duration and better level of hearing.