Learning Effect of Diagnosing Depth of Invasion Using Non-Extension Sign in Early Gastric Cancer.

BACKGROUND: Determining the depth of invasion is important when considering therapeutic strategies for early gastric cancer (EGC). We determined the effects of learning the non-extension sign, that is, an index of T1b2 in EGC, on identifying its depth of invasion. METHODS: Endoscopic images of 40 EGC cases (20 showing positive non-extension sign on endoscopy as T1b2 and 20 showing negative non-extension sign on endoscopy as T1a-T1b1) were randomly displayed on PowerPoint. Participants read endoscopy findings (pretest) and attended a 60-min lecture on how to read the non-extension sign. Then, they read the same images using the non-extension sign as the marker (posttest). The primary endpoint was a change in accuracy rate for determining the depth of invasion before and after attending the lecture, for nonexperts (< 80%). RESULTS: Among 35 endoscopists, 12 were nonexperts; their test results were used for analyses. Accuracy rates for pretest and posttest among nonexperts were 75.2 and 82.5%, respectively, showing a significant increase in the accuracy rate after learning to read the non-extension sign (p = 0.003). CONCLUSION: Nonexperts' diagnostic ability to determine the depth of invasion of EGC improved by learning to read the non-extension sign. Thus, the non-extension sign is considered a simple and useful diagnostic marker.

Strong Photophysical Similarities between Conjugated Polymers and J-aggregates.

The photophysical properties of emissive conjugated polymer (CP) chains are compared to those of linear J-aggregates. The two systems share many properties in common, including a red-shifted absorption spectrum with increasing chain/aggregate length, enhanced radiative decay rates (superradiance) relative to a single monomer/molecule, and several vibronic signatures involving the vinyl-stretching mode common to many conjugated molecules. In particular, the scaling of the 0-0/0-1 photoluminescence ratio and radiative decay rate with the inverse square root of temperature in red-phase polydiacetylene is also characteristic of linear, disorder-free J-aggregates. The strong photophysical resemblance is traced to the excitonic band structure; in one-dimensional direct band gap semiconductors as well as J-aggregates, the exciton band curvature is positive at the gamma point (k = 0).

The red-phase of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV): a disordered HJ-aggregate.

The ratio of the 0-0 to 0-1 peak intensities in the photoluminescence (PL) spectrum of red-phase poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], better known as MEH-PPV, is significantly enhanced relative to the disordered blue-phase and is practically temperature independent in the range from T = 5 K to 180 K. The PL lifetime is similarly temperature independent. The measured trends are accounted for by modeling red-phase MEH-PPV as disordered π-stacks of elongated chains. Using the HJ-aggregate Hamiltonian expanded to include site disorder amongst electrons and holes, the absorption and PL spectra of cofacial MEH-PPV dimers are calculated. The PL 0-0/0-1 line strength ratio directly responds to the competition between intrachain interactions which promote J-aggregate-like behavior (enhanced PL ratio) and interchain interactions which promote H-aggregate-like behavior (attenuated PL ratio). In MEH-PPV aggregates, J-like behavior is favored by a relatively large intrachain exciton bandwidth--roughly an order of magnitude greater than the interchain bandwidth--and the presence of disorder. The latter is essential for allowing 0-0 emission at low temperatures, which is otherwise symmetry forbidden. For Gaussian disorder distributions consistent with the measured (inhomogeneous) line widths of the vibronic peaks in the absorption spectrum, calculations show that the 0-0 peak maintains its dominance over the 0-1 peak, with the PL ratio and radiative lifetime practically independent of temperature, in excellent agreement with experiment. Interestingly, interchain interactions lead only to about a 30% drop in the PL ratio, suggesting that the MEH-PPV π-stacks--and strongly disordered HJ-aggregates in general--can masquerade as single (elongated) chains. Our results may have important applications to other emissive conjugated polymers such as the ß-phase of polyfluorenes.

Contrasting photophysical properties of star-shaped vs linear perylene diimide complexes.

The absorption line shapes of a series of linear and star-shaped perylene diimide (PDI) complexes are evaluated theoretically and compared to experiment. The cyclic trimer and tetrahedral complexes are part of the symmetric series, characterized by a single interchromophoric coupling, J(0), between any two PDI chromophores. The measured spectra of all complexes show pronounced vibronic progressions based on the symmetric ring stretching mode at ~1400 cm(-1). The spectral line shapes are accurately reproduced using a Holstein Hamiltonian parametrized with electronic couplings calculated using time-dependent density functional transition charge densities. Although the "head-to-tail" linear complexes display classic J-aggregate behavior, the star-shaped complexes display a unique photophysical response, which is neither J- nor H-like. In the symmetric N-mers (N = 2-4), absorption and emission are polarized along N - 1 directions in contrast to linear complexes where absorption and emission remain polarized along the long molecular axis. In the symmetric complexes the red-shift of the 0-0 peak with increasing |J(0)|, as well as the initial linear rise of the 0-0/1-0 oscillator strength ratio with increasing |J(0)|, are independent of the number of PDI chromophores, N, and are markedly smaller than what is found in the linear series, where the shifts and ratios depend on N. Moreover, whereas the radiative decay rate, γ(r), scales with N and is therefore superradiant in linear complexes, γ(r) scales with N/(N - 1) in the symmetric complexes. Vibronic/vibrational pair states (two-particle states) are found to profoundly affect the absorption line shapes of both linear and symmetric complexes for sufficiently large coupling.

Designing J- and H-aggregates through wave function overlap engineering: applications to poly(3-hexylthiophene).

A novel mechanism for J- and H-aggregate formation is presented on the basis of wave function overlap (WFO) coupling between neighboring chromophores which supplements the usual through-space (Coulombic) coupling. In cases where the latter is relatively small compared to the former, as might arise for excitons based on molecular transitions with low oscillator strengths, J- vs H-aggregation is determined by the sign of the product D(e)D(h), where D(e) (D(h)) is the coupling between a neutral Frenkel exciton and the charge transfer exciton created through the transfer of an electron (hole) to a neighboring chromophore. Adapting a sign convention based on translational symmetry in a linear array of chromophores, a positive (negative) sign for D(e)D(h) places the bright exciton on the bottom (top) of the exciton band, consistent with J- (H-) aggregation. The J- (H-) aggregates so formed behave as direct (indirect) bandgap semiconductors with vibronic signatures in absorption and photoluminescence that are identical to those displayed by conventional Coulomb coupled aggregates. WFO coupling leading to the mixing of intrachain Frenkel excitons and polaron pairs may be important in conjugated polymer aggregates where the Coulomb coupling practically vanishes with the (conjugation) length of the polymer. Calculations based on octathiophene (8T) dimers show that the eclipsed geometry yields a WFO coupling favoring H-aggregate behavior, although a longitudinal (long-axis) displacement by only 1.5 Å is enough to change the sign of the coupling, leading to J-aggregate behavior. Hence, it should be possible to design thiophene-based polymers which act as J-aggregates with respect to the interchain coupling.

NEFA/nucleobindin-2 is a target autoantigen of the anti-Wa antibody and is associated with transfer RNA.

OBJECTIVES: The anti-Wa antibody found in systemic sclerosis patients reacts with a transfer RNA (tRNA)-associated 48-kDa protein and immunoprecipitates several tRNAs. We investigated the Wa antigen and its binding to tRNA species. METHODS: We performed molecular cloning of the Wa antigen and made its recombinant protein. To investigate Wa antigen distribution in the cell, we performed an indirect immunofluorescence study. To determine the Wa-bound tRNA species, we performed a reverse transcription (RT)-polymerase chain reaction (PCR) using the RNAs immunoprecipitated by anti-Wa antibody as templates, and synthetic primers of mammalian tRNA sequences. To clarify the tissue expression of Wa antigen, we performed quantitative and semi-quantitative PCR of the cDNA. RESULTS: We demonstrated that the Wa antigen was identical to NEFA (DNA binding/EF-hand/acidic amino acid rich region), otherwise known as nucleobindin-2. A full-length and an alternative splice variant cDNA lacking exon 11 were isolated by cloning NEFA cDNA. Anti-Wa-positive sera stained both the nucleus and cytoplasm of HEp-2 cells. RT-PCR suggested that Wa binds at least six tRNA species. In human tissues, NEFA is expressed predominantly in exocrine glands. CONCLUSIONS: We have demonstrated that the Wa antigen is NEFA or nucleobindin-2, which binds specific tRNA species, and is distributed in specific human tissues.

Vibronic coupling in J-aggregates and beyond: a direct means of determining the exciton coherence length from the photoluminescence spectrum.

Exciton coherence in a J-aggregate with exciton−phonon coupling involving a single intramolecular vibration is studied. For linear aggregates with no disorder and periodic boundary conditions, the 0−0 to 0−1 line strength ratio, S(R), corresponding to the low-temperature photoluminescence spectrum is rigorously equal to N/λ2, where N is the number of chromophores comprising the aggregate and λ2 is the Huang−Rhys factor of the coupled vibrational mode. The result is independent of exciton bandwidth and therefore remains exact from the weak to strong exciton−phonon coupling regimes. The simple relation between S(R) and N also holds for more complex morphologies, as long as the transition from the lowest exciton state to the vibrationless ground state is symmetry-allowed. For example, in herringbone aggregates with monoclinic unit cells, the line strength ratio, defined as SR ≡ I(b)(0−0)/I(b)(0−1) (where I(b)(0−0) and I(b)(0−1) correspond to the b-polarized 0−0 and 0−1 line strengths, respectively) is rigorously equal to N/λ2. In the presence of disorder and for T > 0 K, λ2S(R) is closely approximated by the exciton coherence number N(coh), thereby providing a simple and direct way of extracting N(coh) from the photoluminescence spectrum. Increasing temperature in linear J-aggregates (and herringbone aggregates) generally leads to a demise in S(R) and therefore also the exciton coherence size. When no disorder is present, and under the fast scattering and thermodynamic limits, S(R) is equal to N(T)/λ2, where the thermal coherence size is given by N(T) = 1 + [4πω(c)/k(b)T](d/2) for an aggregate of dimension d, where ω(c) is the exciton band curvature at k = 0.

Patients with pulmonary tuberculosis are frequently positive for anti-cyclic citrullinated peptide antibodies, but their sera also react with unmodified arginine-containing peptide.

OBJECTIVE: The anti-cyclic citrullinated peptide (anti-CCP) enzyme-linked immunosorbent assay (ELISA) has high sensitivity and specificity for rheumatoid arthritis (RA). However, detection of anti-CCP in patients with active pulmonary tuberculosis (TB) has recently been reported. To determine whether this activity was specific for the citrullinated residue, the specificity of anti-CCP-positive sera for CCP versus that for unmodified arginine-containing peptide (CAP) was examined in patients with TB and compared with that in patients with RA. METHODS: Anti-CCP and anti-CAP in sera from patients with pulmonary TB (n = 49), RA patients (n = 36), and controls (n = 18) were tested by ELISA. Sera were available at diagnosis from most TB patients. All TB patients were treated with a combination of 2-4 antibiotics for at least 6 months, and sera were collected over time. RESULTS: Anti-CCP was found in 37% of TB patients and in 43% of RA patients. CAP reactivity was more common in TB than in RA. High anti-CCP:anti-CAP ratios (>2.0) were seen far more commonly in anti-CCP-positive RA patients than in anti-CCP-positive TB patients (94% versus 22%). Anti-CCP was inhibited by CCP peptide in sera from RA patients, but not in sera from TB patients. A slight increase in anti-CCP was common after initiating treatment for TB, although the anti-CCP level decreased after 1-2 months. CONCLUSION: Anti-CCP is frequently present in patients with active TB. However, many anti-CCP-positive TB sera also reacted with CAP, and anti-CCP:anti-CAP ratios in TB sera were low. Anti-CCP:anti-CAP ratios should be useful clinically for distinguishing CCP-specific reactivity seen in RA from reactivity with both CCP and CAP frequently seen in pulmonary TB.

Linear mucosal defect may be characteristic of lansoprazole-associated collagenous colitis.

BACKGROUND: Although some cases of collagenous colitis have been induced by lansoprazole (LPZ), the clinicopathologic features of LPZ-associated collagenous colitis have not been elucidated. OBJECTIVE: To elucidate the clinical, endoscopic, and histopathologic features of LPZ-associated collagenous colitis. DESIGN: Retrospective case study. PATIENTS: The subjects were 13 patients with collagenous colitis diagnosed during a period from 2002 to 2007. MAIN OUTCOME MEASUREMENTS: The colonoscopic and histopathologic findings were compared retrospectively between 9 cases of LPZ use (LPZ group) and 4 cases without the use of LPZ (non-LPZ group). RESULTS: A colonoscopy revealed a linear mucosal defect more frequently in the LPZ group (7 of 9 cases [78%]) than in the non-LPZ group (0 of 4 cases [0%], P = .02). Friable mucosa was also noted in 4 patients (44%) in the LPZ group but none in the non-LPZ group. The colonoscopic finding in the non-LPZ group was either normal mucosa or nonspecific minimal abnormalities, whereas patients in the LPZ group had either a linear mucosal defect, mucosal bleeding, or both (P = .001). On histologic examination, the subepithelial collagen band was thicker in patients in the LPZ group than in those in the non-LPZ group (median 45 vs 26.3 mum). All patients in the LPZ group recovered from diarrhea after discontinuance of LPZ. LIMITATION: A small number of patients. CONCLUSIONS: Linear mucosal defects and friable mucosa may be characteristic colonoscopic findings in cases of LPZ-associated collagenous colitis.

Impact of fasting plasma glucose levels on gastric cancer incidence in a general Japanese population: the Hisayama study.

OBJECTIVE: Several studies have shown associations between diabetes and various types of cancer other than gastric cancer. The aim of this cohort study was to evaluate the impact of fasting plasma glucose (FPG) levels on gastric cancer occurrence. RESEARCH DESIGN AND METHODS: A total of 2,466 Japanese subjects aged > or =40 years were stratified into three groups according to FPG tertiles (<5.3 mmol/l, low FPG; 5.3-5.8 mmol/l, modest FPG; >5.8 mmol/l, high FPG) and followed up prospectively for 9 years. RESULTS: During the follow-up, 66 subjects experienced gastric cancer. In men, the age-adjusted incidences were significantly higher in the modest-FPG (7.0 per 1,000 person-years, P < 0.05) and high-FPG (7.2, P < 0.05) groups than in the low-FPG group (2.2). In women, the high-FPG group also had a significantly higher age-adjusted incidence of gastric cancer compared with the low-FPG group (2.5 vs. 0.8, P < 0.05). The multivariate analysis with Cox's proportional hazards model revealed that the risks of gastric cancer in the modest-FPG (relative risk [RR] 2.3 [95% CI 1.1-5.0]) and high-FPG (3.1 [1.5-6.4]) groups were significantly higher than that in the low-FPG group, even after adjusting for other comprehensive risk factors, including Helicobacter pylori status, smoking, and dietary factors. However, this FPG-cancer association was observed only among H. pylori-seropositive subjects. CONCLUSIONS: Our findings suggest that a modest increase in FPG is a risk factor for gastric cancer and that hyperglycemia is a possible cofactor increasing the risk posed by Helicobacter pylori infection.